diff --git a/crates/biome_configuration/src/linter/rules.rs b/crates/biome_configuration/src/linter/rules.rs
index 33ed6308178..03bed2084de 100644
--- a/crates/biome_configuration/src/linter/rules.rs
+++ b/crates/biome_configuration/src/linter/rules.rs
@@ -2674,6 +2674,9 @@ pub struct Nursery {
     #[doc = "Disallow two keys with the same name inside a JSON object."]
     #[serde(skip_serializing_if = "Option::is_none")]
     pub no_duplicate_json_keys: Option<RuleConfiguration<NoDuplicateJsonKeys>>,
+    #[doc = "Disallow duplicate selectors. This rule checks for two types of duplication:"]
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub no_duplicate_selectors: Option<RuleConfiguration<NoDuplicateSelectors>>,
     #[doc = "Disallow duplicate selectors within keyframe blocks."]
     #[serde(skip_serializing_if = "Option::is_none")]
     pub no_duplicate_selectors_keyframe_block:
@@ -2777,6 +2780,7 @@ impl Nursery {
         "noDuplicateElseIf",
         "noDuplicateFontNames",
         "noDuplicateJsonKeys",
+        "noDuplicateSelectors",
         "noDuplicateSelectorsKeyframeBlock",
         "noEvolvingAny",
         "noFlatMapIdentity",
@@ -2809,6 +2813,7 @@ impl Nursery {
         "noDuplicateElseIf",
         "noDuplicateFontNames",
         "noDuplicateJsonKeys",
+        "noDuplicateSelectors",
         "noDuplicateSelectorsKeyframeBlock",
         "noEvolvingAny",
         "noFlatMapIdentity",
@@ -2831,12 +2836,13 @@ impl Nursery {
         RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[10]),
         RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[11]),
         RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[12]),
-        RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[18]),
-        RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[20]),
+        RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[13]),
+        RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[19]),
         RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[21]),
         RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[22]),
-        RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[29]),
+        RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[23]),
         RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[30]),
+        RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[31]),
     ];
     const ALL_RULES_AS_FILTERS: &'static [RuleFilter<'static>] = &[
         RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[0]),
@@ -2872,6 +2878,7 @@ impl Nursery {
         RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[30]),
         RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[31]),
         RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[32]),
+        RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[33]),
     ];
     #[doc = r" Retrieves the recommended rules"]
     pub(crate) fn is_recommended_true(&self) -> bool {
@@ -2933,126 +2940,131 @@ impl Nursery {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[8]));
             }
         }
-        if let Some(rule) = self.no_duplicate_selectors_keyframe_block.as_ref() {
+        if let Some(rule) = self.no_duplicate_selectors.as_ref() {
             if rule.is_enabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[9]));
             }
         }
-        if let Some(rule) = self.no_evolving_any.as_ref() {
+        if let Some(rule) = self.no_duplicate_selectors_keyframe_block.as_ref() {
             if rule.is_enabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[10]));
             }
         }
-        if let Some(rule) = self.no_flat_map_identity.as_ref() {
+        if let Some(rule) = self.no_evolving_any.as_ref() {
             if rule.is_enabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[11]));
             }
         }
-        if let Some(rule) = self.no_important_in_keyframe.as_ref() {
+        if let Some(rule) = self.no_flat_map_identity.as_ref() {
             if rule.is_enabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[12]));
             }
         }
-        if let Some(rule) = self.no_misplaced_assertion.as_ref() {
+        if let Some(rule) = self.no_important_in_keyframe.as_ref() {
             if rule.is_enabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[13]));
             }
         }
-        if let Some(rule) = self.no_nodejs_modules.as_ref() {
+        if let Some(rule) = self.no_misplaced_assertion.as_ref() {
             if rule.is_enabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[14]));
             }
         }
-        if let Some(rule) = self.no_react_specific_props.as_ref() {
+        if let Some(rule) = self.no_nodejs_modules.as_ref() {
             if rule.is_enabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[15]));
             }
         }
-        if let Some(rule) = self.no_restricted_imports.as_ref() {
+        if let Some(rule) = self.no_react_specific_props.as_ref() {
             if rule.is_enabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[16]));
             }
         }
-        if let Some(rule) = self.no_undeclared_dependencies.as_ref() {
+        if let Some(rule) = self.no_restricted_imports.as_ref() {
             if rule.is_enabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[17]));
             }
         }
-        if let Some(rule) = self.no_unknown_function.as_ref() {
+        if let Some(rule) = self.no_undeclared_dependencies.as_ref() {
             if rule.is_enabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[18]));
             }
         }
-        if let Some(rule) = self.no_unknown_property.as_ref() {
+        if let Some(rule) = self.no_unknown_function.as_ref() {
             if rule.is_enabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[19]));
             }
         }
-        if let Some(rule) = self.no_unknown_selector_pseudo_element.as_ref() {
+        if let Some(rule) = self.no_unknown_property.as_ref() {
             if rule.is_enabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[20]));
             }
         }
-        if let Some(rule) = self.no_unknown_unit.as_ref() {
+        if let Some(rule) = self.no_unknown_selector_pseudo_element.as_ref() {
             if rule.is_enabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[21]));
             }
         }
-        if let Some(rule) = self.no_unmatchable_anb_selector.as_ref() {
+        if let Some(rule) = self.no_unknown_unit.as_ref() {
             if rule.is_enabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[22]));
             }
         }
-        if let Some(rule) = self.no_useless_string_concat.as_ref() {
+        if let Some(rule) = self.no_unmatchable_anb_selector.as_ref() {
             if rule.is_enabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[23]));
             }
         }
-        if let Some(rule) = self.no_useless_undefined_initialization.as_ref() {
+        if let Some(rule) = self.no_useless_string_concat.as_ref() {
             if rule.is_enabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[24]));
             }
         }
-        if let Some(rule) = self.use_array_literals.as_ref() {
+        if let Some(rule) = self.no_useless_undefined_initialization.as_ref() {
             if rule.is_enabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[25]));
             }
         }
-        if let Some(rule) = self.use_consistent_builtin_instantiation.as_ref() {
+        if let Some(rule) = self.use_array_literals.as_ref() {
             if rule.is_enabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[26]));
             }
         }
-        if let Some(rule) = self.use_default_switch_clause.as_ref() {
+        if let Some(rule) = self.use_consistent_builtin_instantiation.as_ref() {
             if rule.is_enabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[27]));
             }
         }
-        if let Some(rule) = self.use_explicit_length_check.as_ref() {
+        if let Some(rule) = self.use_default_switch_clause.as_ref() {
             if rule.is_enabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[28]));
             }
         }
-        if let Some(rule) = self.use_focusable_interactive.as_ref() {
+        if let Some(rule) = self.use_explicit_length_check.as_ref() {
             if rule.is_enabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[29]));
             }
         }
-        if let Some(rule) = self.use_generic_font_names.as_ref() {
+        if let Some(rule) = self.use_focusable_interactive.as_ref() {
             if rule.is_enabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[30]));
             }
         }
-        if let Some(rule) = self.use_import_restrictions.as_ref() {
+        if let Some(rule) = self.use_generic_font_names.as_ref() {
             if rule.is_enabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[31]));
             }
         }
-        if let Some(rule) = self.use_sorted_classes.as_ref() {
+        if let Some(rule) = self.use_import_restrictions.as_ref() {
             if rule.is_enabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[32]));
             }
         }
+        if let Some(rule) = self.use_sorted_classes.as_ref() {
+            if rule.is_enabled() {
+                index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[33]));
+            }
+        }
         index_set
     }
     pub(crate) fn get_disabled_rules(&self) -> IndexSet<RuleFilter> {
@@ -3102,126 +3114,131 @@ impl Nursery {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[8]));
             }
         }
-        if let Some(rule) = self.no_duplicate_selectors_keyframe_block.as_ref() {
+        if let Some(rule) = self.no_duplicate_selectors.as_ref() {
             if rule.is_disabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[9]));
             }
         }
-        if let Some(rule) = self.no_evolving_any.as_ref() {
+        if let Some(rule) = self.no_duplicate_selectors_keyframe_block.as_ref() {
             if rule.is_disabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[10]));
             }
         }
-        if let Some(rule) = self.no_flat_map_identity.as_ref() {
+        if let Some(rule) = self.no_evolving_any.as_ref() {
             if rule.is_disabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[11]));
             }
         }
-        if let Some(rule) = self.no_important_in_keyframe.as_ref() {
+        if let Some(rule) = self.no_flat_map_identity.as_ref() {
             if rule.is_disabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[12]));
             }
         }
-        if let Some(rule) = self.no_misplaced_assertion.as_ref() {
+        if let Some(rule) = self.no_important_in_keyframe.as_ref() {
             if rule.is_disabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[13]));
             }
         }
-        if let Some(rule) = self.no_nodejs_modules.as_ref() {
+        if let Some(rule) = self.no_misplaced_assertion.as_ref() {
             if rule.is_disabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[14]));
             }
         }
-        if let Some(rule) = self.no_react_specific_props.as_ref() {
+        if let Some(rule) = self.no_nodejs_modules.as_ref() {
             if rule.is_disabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[15]));
             }
         }
-        if let Some(rule) = self.no_restricted_imports.as_ref() {
+        if let Some(rule) = self.no_react_specific_props.as_ref() {
             if rule.is_disabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[16]));
             }
         }
-        if let Some(rule) = self.no_undeclared_dependencies.as_ref() {
+        if let Some(rule) = self.no_restricted_imports.as_ref() {
             if rule.is_disabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[17]));
             }
         }
-        if let Some(rule) = self.no_unknown_function.as_ref() {
+        if let Some(rule) = self.no_undeclared_dependencies.as_ref() {
             if rule.is_disabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[18]));
             }
         }
-        if let Some(rule) = self.no_unknown_property.as_ref() {
+        if let Some(rule) = self.no_unknown_function.as_ref() {
             if rule.is_disabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[19]));
             }
         }
-        if let Some(rule) = self.no_unknown_selector_pseudo_element.as_ref() {
+        if let Some(rule) = self.no_unknown_property.as_ref() {
             if rule.is_disabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[20]));
             }
         }
-        if let Some(rule) = self.no_unknown_unit.as_ref() {
+        if let Some(rule) = self.no_unknown_selector_pseudo_element.as_ref() {
             if rule.is_disabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[21]));
             }
         }
-        if let Some(rule) = self.no_unmatchable_anb_selector.as_ref() {
+        if let Some(rule) = self.no_unknown_unit.as_ref() {
             if rule.is_disabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[22]));
             }
         }
-        if let Some(rule) = self.no_useless_string_concat.as_ref() {
+        if let Some(rule) = self.no_unmatchable_anb_selector.as_ref() {
             if rule.is_disabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[23]));
             }
         }
-        if let Some(rule) = self.no_useless_undefined_initialization.as_ref() {
+        if let Some(rule) = self.no_useless_string_concat.as_ref() {
             if rule.is_disabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[24]));
             }
         }
-        if let Some(rule) = self.use_array_literals.as_ref() {
+        if let Some(rule) = self.no_useless_undefined_initialization.as_ref() {
             if rule.is_disabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[25]));
             }
         }
-        if let Some(rule) = self.use_consistent_builtin_instantiation.as_ref() {
+        if let Some(rule) = self.use_array_literals.as_ref() {
             if rule.is_disabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[26]));
             }
         }
-        if let Some(rule) = self.use_default_switch_clause.as_ref() {
+        if let Some(rule) = self.use_consistent_builtin_instantiation.as_ref() {
             if rule.is_disabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[27]));
             }
         }
-        if let Some(rule) = self.use_explicit_length_check.as_ref() {
+        if let Some(rule) = self.use_default_switch_clause.as_ref() {
             if rule.is_disabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[28]));
             }
         }
-        if let Some(rule) = self.use_focusable_interactive.as_ref() {
+        if let Some(rule) = self.use_explicit_length_check.as_ref() {
             if rule.is_disabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[29]));
             }
         }
-        if let Some(rule) = self.use_generic_font_names.as_ref() {
+        if let Some(rule) = self.use_focusable_interactive.as_ref() {
             if rule.is_disabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[30]));
             }
         }
-        if let Some(rule) = self.use_import_restrictions.as_ref() {
+        if let Some(rule) = self.use_generic_font_names.as_ref() {
             if rule.is_disabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[31]));
             }
         }
-        if let Some(rule) = self.use_sorted_classes.as_ref() {
+        if let Some(rule) = self.use_import_restrictions.as_ref() {
             if rule.is_disabled() {
                 index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[32]));
             }
         }
+        if let Some(rule) = self.use_sorted_classes.as_ref() {
+            if rule.is_disabled() {
+                index_set.insert(RuleFilter::Rule(Self::GROUP_NAME, Self::GROUP_RULES[33]));
+            }
+        }
         index_set
     }
     #[doc = r" Checks if, given a rule name, matches one of the rules contained in this category"]
@@ -3294,6 +3311,10 @@ impl Nursery {
                 .no_duplicate_json_keys
                 .as_ref()
                 .map(|conf| (conf.level(), conf.get_options())),
+            "noDuplicateSelectors" => self
+                .no_duplicate_selectors
+                .as_ref()
+                .map(|conf| (conf.level(), conf.get_options())),
             "noDuplicateSelectorsKeyframeBlock" => self
                 .no_duplicate_selectors_keyframe_block
                 .as_ref()
diff --git a/crates/biome_css_analyze/src/lint/nursery.rs b/crates/biome_css_analyze/src/lint/nursery.rs
index c7ddaee16c9..b9cdbb2e259 100644
--- a/crates/biome_css_analyze/src/lint/nursery.rs
+++ b/crates/biome_css_analyze/src/lint/nursery.rs
@@ -6,6 +6,7 @@ pub mod no_color_invalid_hex;
 pub mod no_css_empty_block;
 pub mod no_duplicate_at_import_rules;
 pub mod no_duplicate_font_names;
+pub mod no_duplicate_selectors;
 pub mod no_duplicate_selectors_keyframe_block;
 pub mod no_important_in_keyframe;
 pub mod no_unknown_function;
@@ -23,6 +24,7 @@ declare_group! {
             self :: no_css_empty_block :: NoCssEmptyBlock ,
             self :: no_duplicate_at_import_rules :: NoDuplicateAtImportRules ,
             self :: no_duplicate_font_names :: NoDuplicateFontNames ,
+            self :: no_duplicate_selectors :: NoDuplicateSelectors ,
             self :: no_duplicate_selectors_keyframe_block :: NoDuplicateSelectorsKeyframeBlock ,
             self :: no_important_in_keyframe :: NoImportantInKeyframe ,
             self :: no_unknown_function :: NoUnknownFunction ,
diff --git a/crates/biome_css_analyze/src/lint/nursery/no_duplicate_selectors.rs b/crates/biome_css_analyze/src/lint/nursery/no_duplicate_selectors.rs
new file mode 100644
index 00000000000..6d44fcaaf72
--- /dev/null
+++ b/crates/biome_css_analyze/src/lint/nursery/no_duplicate_selectors.rs
@@ -0,0 +1,395 @@
+use std::borrow::Borrow;
+use std::collections::HashSet;
+use std::hash::{DefaultHasher, Hash, Hasher};
+use std::vec;
+
+use biome_analyze::Ast;
+use biome_analyze::{context::RuleContext, declare_rule, Rule, RuleDiagnostic, RuleSource};
+use biome_console::markup;
+use biome_css_syntax::{
+    AnyCssAtRule, AnyCssRelativeSelector, AnyCssRule, AnyCssSelector, CssComplexSelector,
+    CssRelativeSelector, CssRelativeSelectorList, CssRoot, CssSelectorList, CssSyntaxNode,
+};
+use biome_deserialize_macros::Deserializable;
+use biome_rowan::{declare_node_union, AstNode, SyntaxNodeCast};
+
+use serde::{Deserialize, Serialize};
+
+declare_rule! {
+    /// Disallow duplicate selectors. This rule checks for two types of duplication:
+    /// - Duplication of a selector list within a stylesheet, e.g. `a, b {} a, b {}`. Duplicates are found even if the selectors come in different orders or have different spacing, e.g. `a d, b > c {} b>c, a d {}`.
+    /// - Duplication of a single selector with a rule's selector list, e.g. `a, b, a {}`.  (See options below, this is disabled by default)
+    ///
+    /// The same selector is allowed to repeat in the following circumstances:
+    /// - It is used in different selector lists, e.g. `a {} a, b {}`.
+    /// - The duplicates are in rules with different parent nodes, e.g. inside and outside of a media query.
+    ///
+    /// This rule resolves nested selectors. So `a b {} a { & b {} }` counts as a problem, because the resolved selectors end up with a duplicate.
+    ///
+    /// ## Examples
+    ///
+    /// ### Invalid
+    ///
+    /// ```css,expect_diagnostic
+    /// .abc,
+    /// .def,
+    /// .abc { /* declaration */ }
+    /// ```
+    ///
+    /// ### Valid
+    ///
+    /// ```
+    /// .foo { /* declaration */ }
+    /// .bar { /* declaration */ }
+    /// ```
+    ///
+    /// ## Options
+    ///
+    /// If true, disallow duplicate selectors within selector lists. The following settings:
+    ///
+    /// ```json5, ignore
+    /// {
+    ///     "noDuplicateSelectors": {
+    ///         "options": {
+    ///           "disallowInList": true
+    ///         }
+    ///     }
+    /// }
+    /// ```
+    ///
+    /// Will result in the following failing:
+    ///
+    /// ```css, ignore
+    /// input, textarea {}; textarea {}
+    /// ```
+    ///
+    pub NoDuplicateSelectors {
+        version: "next",
+        name: "noDuplicateSelectors",
+        recommended: true,
+        sources: &[RuleSource::Stylelint("no-duplicate-selectors")],
+    }
+}
+
+#[derive(Debug, Default, Clone, Deserialize, Deserializable, Eq, PartialEq, Serialize)]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+#[serde(rename_all = "camelCase", deny_unknown_fields)]
+pub struct NoDuplicateSelectorsOptions {
+    /// If set to `true` this rule will check for duplicate selectors within selector lists.
+    pub disallow_in_list: bool,
+}
+
+declare_node_union! {
+    pub AnySelectorLike = AnyCssSelector | AnyCssRelativeSelector
+}
+
+/// Object containing the resolved selector and the relative node for that resolved selector.
+///
+/// This struct has a hash function which returns the hash of `selector_node`.
+#[derive(Debug, Eq)]
+struct ResolvedSelector {
+    selector_text: String,
+    selector_node: CssSyntaxNode,
+}
+
+impl PartialEq for ResolvedSelector {
+    fn eq(&self, other: &ResolvedSelector) -> bool {
+        self.selector_text == other.selector_text
+    }
+}
+impl Hash for ResolvedSelector {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.selector_text.hash(state);
+    }
+}
+impl Borrow<String> for ResolvedSelector {
+    fn borrow(&self) -> &String {
+        &self.selector_text
+    }
+}
+
+pub struct DuplicateSelector {
+    first: CssSyntaxNode,
+    duplicate: CssSyntaxNode,
+}
+
+impl Rule for NoDuplicateSelectors {
+    type Query = Ast<CssRoot>;
+    type State = DuplicateSelector;
+    type Signals = Vec<Self::State>;
+    type Options = NoDuplicateSelectorsOptions;
+
+    fn run(ctx: &RuleContext<Self>) -> Vec<Self::State> {
+        let node = ctx.query();
+        let options = ctx.options();
+
+        let mut resolved_list: HashSet<ResolvedSelector> = HashSet::new();
+        let mut output: Vec<DuplicateSelector> = vec![];
+
+        if options.disallow_in_list {
+            let selectors = node
+                .rules()
+                .syntax()
+                .descendants()
+                .filter_map(|x| AnySelectorLike::cast_ref(&x));
+
+            for (selector, selector_list) in selectors.filter_map(|selector| {
+                let parent = selector.clone().into_syntax().parent()?;
+                if parent.clone().cast::<CssComplexSelector>().is_some()
+                    || parent.clone().cast::<CssRelativeSelector>().is_some()
+                {
+                    return None;
+                }
+                Some((selector, parent))
+            }) {
+                let Some(this_rule) = selector_list.parent() else {
+                    continue;
+                };
+
+                let selector_text = match selector.clone() {
+                    AnySelectorLike::AnyCssSelector(selector) => {
+                        normalize_complex_selector(selector)
+                    }
+                    AnySelectorLike::AnyCssRelativeSelector(selector) => selector.text(),
+                };
+
+                for r in resolve_nested_selectors(selector_text, this_rule) {
+                    let split: Vec<&str> = r.split_whitespace().collect();
+                    let normalized = split.join(" ").to_lowercase();
+
+                    if let Some(first) = resolved_list.get(&normalized) {
+                        output.push(DuplicateSelector {
+                            first: first.selector_node.clone(),
+                            duplicate: selector.clone().into_syntax(),
+                        });
+                    } else {
+                        resolved_list.insert(ResolvedSelector {
+                            selector_text: normalized.clone(),
+                            selector_node: selector.clone().into_syntax(),
+                        });
+                    }
+                }
+            }
+        } else {
+            // Union node with CssSelectorList and CssRelativeSelectorList does not have overlapping From/Into
+            let selector_lists = node.rules().syntax().descendants().filter(|x| {
+                x.clone().cast::<CssSelectorList>().is_some()
+                    || x.clone().cast::<CssRelativeSelectorList>().is_some()
+            });
+
+            for (selector_list, rule) in selector_lists.filter_map(|selector_list| {
+                let parent = selector_list.clone().parent()?;
+                Some((selector_list, parent))
+            }) {
+                let mut this_list_resolved_list: HashSet<ResolvedSelector> = HashSet::new();
+
+                let mut selector_list_mapped: Vec<String> = selector_list
+                    .clone()
+                    .children()
+                    .filter_map(|child| {
+                        let selector_text = if let Some(selector) = AnyCssSelector::cast_ref(&child)
+                        {
+                            normalize_complex_selector(selector.clone())
+                        } else {
+                            child
+                                .clone()
+                                .cast::<AnyCssRelativeSelector>()
+                                .unwrap()
+                                .text()
+                        };
+
+                        if let Some(first) = this_list_resolved_list.get(&selector_text) {
+                            output.push(DuplicateSelector {
+                                first: first.selector_node.clone(),
+                                duplicate: child.clone(),
+                            });
+                            return None;
+                        }
+
+                        this_list_resolved_list.insert(ResolvedSelector {
+                            selector_text: selector_text.clone(),
+                            selector_node: child,
+                        });
+                        Some(selector_text)
+                    })
+                    .collect();
+                selector_list_mapped.sort();
+
+                for r in resolve_nested_selectors(selector_list_mapped.join(","), rule) {
+                    let split: Vec<&str> = r.split_whitespace().collect();
+                    let normalized = split.join(" ").to_lowercase();
+                    if let Some(first) = resolved_list.get(&normalized) {
+                        output.push(DuplicateSelector {
+                            first: first.selector_node.clone(),
+                            duplicate: selector_list.clone(),
+                        });
+                    } else {
+                        resolved_list.insert(ResolvedSelector {
+                            selector_text: normalized.clone(),
+                            selector_node: selector_list.clone(),
+                        });
+                    }
+                }
+            }
+        }
+        output
+    }
+
+    fn diagnostic(_: &RuleContext<Self>, node: &Self::State) -> Option<RuleDiagnostic> {
+        let duplicate_text = if let Some(duplicate) = AnySelectorLike::cast_ref(&node.duplicate) {
+            duplicate.text()
+        } else if let Some(duplicate) = CssSelectorList::cast_ref(&node.duplicate) {
+            duplicate.text()
+        } else if let Some(duplicate) = CssRelativeSelectorList::cast_ref(&node.duplicate) {
+            duplicate.text()
+        } else {
+            node.duplicate.to_string()
+        };
+
+        Some(
+            RuleDiagnostic::new(
+                rule_category!(),
+                node.duplicate.text_trimmed_range(),
+                markup! {
+                    "Duplicate selectors may result in unintentionally overriding rules: "<Emphasis>{ duplicate_text }</Emphasis>
+                },
+            )
+            .detail(node.first.text_trimmed_range(), "Please consider moving the rule's contents to the first occurence:")
+            .note(markup! {
+                "Remove duplicate selectors within the rule"
+            }),
+        )
+    }
+}
+
+/// Resolves nested selectors into an equivalent flat selector.
+/// If there is no parent rule, return the selector string originally passed.
+/// E.g.
+/// ```css, ignore
+/// a { b { c { /* declaration */ } } }
+/// ```
+///
+/// is resolved to:
+/// ```css, ignore
+/// a b c {
+///     /* declaration */
+/// }
+/// ```
+///
+/// When trying to resolve this_rule of type [AnyCssAtRule], this function will generate a hash to replace the selector name:
+/// ```css, ignore
+/// @media print {
+///     selector { /* declaration */}
+/// }
+/// ```
+///
+/// is resolved to:
+/// ```css, ignore
+/// <hash> selector { /* declaration */}
+/// ```
+///
+/// [AnyCssAtRule] is resolved based on the text range.
+/// The same rule will not be resolved to the same hash because these are considered to belong to a separate context.
+///
+/// Returns the resolved selector as a string.
+fn resolve_nested_selectors(selector: String, this_rule: CssSyntaxNode) -> Vec<String> {
+    let mut parent_selectors: Vec<String> = vec![];
+    let parent_rule = this_rule.parent().and_then(|parent| parent.grand_parent());
+
+    match &parent_rule {
+        None => vec![selector],
+        Some(parent_rule) => {
+            if let Some(parent_rule) = AnyCssAtRule::cast_ref(parent_rule) {
+                let mut hasher = DefaultHasher::new();
+                parent_rule.range().hash(&mut hasher);
+                // Each @rule is unique scope
+                // Use a hash to create the comparable scope
+                parent_selectors.push(hasher.finish().to_string());
+            } else if let Some(parent_rule) = AnyCssRule::cast_ref(parent_rule) {
+                match parent_rule {
+                    AnyCssRule::CssNestedQualifiedRule(parent_rule) => {
+                        parent_selectors.extend(
+                            parent_rule
+                                .prelude()
+                                .into_iter()
+                                .filter_map(|selector| selector.ok())
+                                .map(|selector| selector.text()),
+                        );
+                    }
+                    AnyCssRule::CssQualifiedRule(parent_rule) => {
+                        parent_selectors.extend(
+                            parent_rule
+                                .prelude()
+                                .into_iter()
+                                .filter_map(|selector| selector.ok())
+                                .map(|selector| selector.text()),
+                        );
+                    }
+                    _ => {
+                        // Bogus rules are not handled
+                        // AtRule is handled by AnyCssAtRule above
+                    }
+                }
+            }
+
+            let resolved_selectors: Vec<String> =
+                parent_selectors
+                    .iter()
+                    .fold(vec![], |result: Vec<String>, parent_selector| {
+                        if selector.contains('&') {
+                            let resolved_parent_selectors = resolve_nested_selectors(
+                                parent_selector.to_string(),
+                                parent_rule.clone(),
+                            );
+                            let resolved = resolved_parent_selectors
+                                .into_iter()
+                                .map(|newly_resolved| selector.replace('&', &newly_resolved))
+                                .collect();
+                            [result, resolved].concat()
+                        } else {
+                            let combined_selectors = parent_selector.to_owned() + " " + &selector;
+                            let resolved =
+                                resolve_nested_selectors(combined_selectors, parent_rule.clone());
+                            [result, resolved].concat()
+                        }
+                    });
+            if !resolved_selectors.is_empty() {
+                return resolved_selectors;
+            }
+            vec![selector]
+        }
+    }
+}
+
+/// Checks if [AnyCssSelector] can be cast to [CssComplexSelector].
+/// If it is able to cast, trim the combinator, e.g.
+///
+/// ``` css, ignore
+/// a > b, c  > d { /* declaration */ }
+/// ```
+///
+/// is normalized to:
+/// ``` css, ignore
+/// a>b, c>d { /* declaration */ }
+/// ```
+///
+/// It will return `selector.text()` if it is unable to cast.
+/// Returns the selector as a string.
+fn normalize_complex_selector(selector: AnyCssSelector) -> String {
+    let mut selector_text = String::new();
+
+    if let AnyCssSelector::CssComplexSelector(complex_selector) = selector {
+        if let Ok(left) = complex_selector.left() {
+            selector_text.push_str(&left.text());
+        }
+        if let Ok(combinator) = complex_selector.combinator() {
+            let combinator = combinator.text_trimmed();
+            selector_text.push_str(combinator);
+        }
+        if let Ok(right) = complex_selector.right() {
+            selector_text.push_str(&right.text());
+        }
+        return selector_text;
+    }
+    selector.text()
+}
diff --git a/crates/biome_css_analyze/src/options.rs b/crates/biome_css_analyze/src/options.rs
index 1f9b8d11202..054eb9a669b 100644
--- a/crates/biome_css_analyze/src/options.rs
+++ b/crates/biome_css_analyze/src/options.rs
@@ -9,6 +9,8 @@ pub type NoCssEmptyBlock =
 pub type NoDuplicateAtImportRules = < lint :: nursery :: no_duplicate_at_import_rules :: NoDuplicateAtImportRules as biome_analyze :: Rule > :: Options ;
 pub type NoDuplicateFontNames =
     <lint::nursery::no_duplicate_font_names::NoDuplicateFontNames as biome_analyze::Rule>::Options;
+pub type NoDuplicateSelectors =
+    <lint::nursery::no_duplicate_selectors::NoDuplicateSelectors as biome_analyze::Rule>::Options;
 pub type NoDuplicateSelectorsKeyframeBlock = < lint :: nursery :: no_duplicate_selectors_keyframe_block :: NoDuplicateSelectorsKeyframeBlock as biome_analyze :: Rule > :: Options ;
 pub type NoImportantInKeyframe = < lint :: nursery :: no_important_in_keyframe :: NoImportantInKeyframe as biome_analyze :: Rule > :: Options ;
 pub type NoUnknownFunction =
diff --git a/crates/biome_css_analyze/tests/specs/nursery/noDuplicateSelectors/disallowInList.css b/crates/biome_css_analyze/tests/specs/nursery/noDuplicateSelectors/disallowInList.css
new file mode 100644
index 00000000000..83019dd5248
--- /dev/null
+++ b/crates/biome_css_analyze/tests/specs/nursery/noDuplicateSelectors/disallowInList.css
@@ -0,0 +1,19 @@
+/* valid cases: should not error */
+th, td {}; tr {}
+*::a {}; a {}
+*::c, b {}; c {}
+d e, f {}; d {}
+
+/* duplicate within a grouping selector */
+input, textarea {}; textarea {}
+
+/* duplicate within a grouping selector, reversed */
+button {}; selector, button {}
+
+/* duplicate within a grouping selector. multiline */
+span, div {};
+ h1, section {};
+h1 {}
+
+/* test regular case for regression */
+v w, x>test {} v { w {} } x > test {}
\ No newline at end of file
diff --git a/crates/biome_css_analyze/tests/specs/nursery/noDuplicateSelectors/disallowInList.css.snap.new b/crates/biome_css_analyze/tests/specs/nursery/noDuplicateSelectors/disallowInList.css.snap.new
new file mode 100644
index 00000000000..437cbd8af56
--- /dev/null
+++ b/crates/biome_css_analyze/tests/specs/nursery/noDuplicateSelectors/disallowInList.css.snap.new
@@ -0,0 +1,142 @@
+---
+source: crates/biome_css_analyze/tests/spec_tests.rs
+assertion_line: 83
+expression: disallowInList.css
+---
+# Input
+```css
+/* valid cases: should not error */
+th, td {}; tr {}
+*::a {}; a {}
+*::c, b {}; c {}
+d e, f {}; d {}
+
+/* duplicate within a grouping selector */
+input, textarea {}; textarea {}
+
+/* duplicate within a grouping selector, reversed */
+button {}; selector, button {}
+
+/* duplicate within a grouping selector. multiline */
+span, div {};
+ h1, section {};
+h1 {}
+
+/* test regular case for regression */
+v w, x>test {} v { w {} } x > test {}
+```
+
+# Diagnostics
+```
+disallowInList.css:8:21 lint/nursery/noDuplicateSelectors ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  ! Duplicate selectors may result in unintentionally overriding rules: textarea
+  
+     7 │ /* duplicate within a grouping selector */
+   > 8 │ input, textarea {}; textarea {}
+       │                     ^^^^^^^^
+     9 │ 
+    10 │ /* duplicate within a grouping selector, reversed */
+  
+  i Please consider moving the rule's contents to the first occurence:
+  
+     7 │ /* duplicate within a grouping selector */
+   > 8 │ input, textarea {}; textarea {}
+       │        ^^^^^^^^
+     9 │ 
+    10 │ /* duplicate within a grouping selector, reversed */
+  
+  i Remove duplicate selectors within the rule
+  
+
+```
+
+```
+disallowInList.css:11:22 lint/nursery/noDuplicateSelectors ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  ! Duplicate selectors may result in unintentionally overriding rules: button
+  
+    10 │ /* duplicate within a grouping selector, reversed */
+  > 11 │ button {}; selector, button {}
+       │                      ^^^^^^
+    12 │ 
+    13 │ /* duplicate within a grouping selector. multiline */
+  
+  i Please consider moving the rule's contents to the first occurence:
+  
+    10 │ /* duplicate within a grouping selector, reversed */
+  > 11 │ button {}; selector, button {}
+       │ ^^^^^^
+    12 │ 
+    13 │ /* duplicate within a grouping selector. multiline */
+  
+  i Remove duplicate selectors within the rule
+  
+
+```
+
+```
+disallowInList.css:16:1 lint/nursery/noDuplicateSelectors ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  ! Duplicate selectors may result in unintentionally overriding rules: h1
+  
+    14 │ span, div {};
+    15 │  h1, section {};
+  > 16 │ h1 {}
+       │ ^^
+    17 │ 
+    18 │ /* test regular case for regression */
+  
+  i Please consider moving the rule's contents to the first occurence:
+  
+    13 │ /* duplicate within a grouping selector. multiline */
+    14 │ span, div {};
+  > 15 │  h1, section {};
+       │  ^^
+    16 │ h1 {}
+    17 │ 
+  
+  i Remove duplicate selectors within the rule
+  
+
+```
+
+```
+disallowInList.css:19:20 lint/nursery/noDuplicateSelectors ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  ! Duplicate selectors may result in unintentionally overriding rules: w
+  
+    18 │ /* test regular case for regression */
+  > 19 │ v w, x>test {} v { w {} } x > test {}
+       │                    ^
+  
+  i Please consider moving the rule's contents to the first occurence:
+  
+    18 │ /* test regular case for regression */
+  > 19 │ v w, x>test {} v { w {} } x > test {}
+       │ ^^^
+  
+  i Remove duplicate selectors within the rule
+  
+
+```
+
+```
+disallowInList.css:19:27 lint/nursery/noDuplicateSelectors ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  ! Duplicate selectors may result in unintentionally overriding rules: x > test
+  
+    18 │ /* test regular case for regression */
+  > 19 │ v w, x>test {} v { w {} } x > test {}
+       │                           ^^^^^^^^
+  
+  i Please consider moving the rule's contents to the first occurence:
+  
+    18 │ /* test regular case for regression */
+  > 19 │ v w, x>test {} v { w {} } x > test {}
+       │      ^^^^^^
+  
+  i Remove duplicate selectors within the rule
+  
+
+```
diff --git a/crates/biome_css_analyze/tests/specs/nursery/noDuplicateSelectors/disallowInList.options.json b/crates/biome_css_analyze/tests/specs/nursery/noDuplicateSelectors/disallowInList.options.json
new file mode 100644
index 00000000000..1c5b1b9db7d
--- /dev/null
+++ b/crates/biome_css_analyze/tests/specs/nursery/noDuplicateSelectors/disallowInList.options.json
@@ -0,0 +1,15 @@
+{
+    "$schema": "../../../../../../packages/@biomejs/biome/configuration_schema.json",
+    "linter": {
+        "rules": {
+            "nursery": {
+                "noDuplicateSelectors": {
+                    "level": "error",
+                    "options": {
+                        "disallowInList": true
+                   }
+                }
+            }
+        }
+    }
+}
diff --git a/crates/biome_css_analyze/tests/specs/nursery/noDuplicateSelectors/invalid.css b/crates/biome_css_analyze/tests/specs/nursery/noDuplicateSelectors/invalid.css
new file mode 100644
index 00000000000..a7615dcec71
--- /dev/null
+++ b/crates/biome_css_analyze/tests/specs/nursery/noDuplicateSelectors/invalid.css
@@ -0,0 +1,51 @@
+/* duplicate within one rule's selector list */
+a, a {}
+
+/* duplicate within one rule's selector list. multiline */
+b,
+b {}
+
+/* duplicate within one rule's selector list. multiline */
+c,
+d,
+d {}
+
+/* duplicated selectors within one rule's selector list. 2 duplicates */
+.e,
+.e,
+.e {}
+
+/* duplicate simple selectors with another rule between */
+f {} g {} f {}
+
+/* duplicate simple selectors with another rule between */
+h {}
+i {}
+h {}
+
+/* duplicate selector lists with different order */
+j, k {} k, j {}
+
+/* duplicate selectors with multiple components */
+m n {}
+m n {}
+
+/* essentially duplicate selector lists with varied spacing */
+.foo   p, q > .bar,
+#baz {}
+  #baz,
+  .foo     p,q>.bar {}
+
+/* duplicate within a media query, in the same rule */
+s {}
+@media print { s, s {} }
+
+/* duplicate within a media query, in different rules */
+t {}
+@media screen and (min-width: 900px) { t {} t {} }
+
+/* duplicate caused by nesting */
+v w {} v { w {} }
+
+/* duplicate caused by &-parent selector */
+x { & {} }
\ No newline at end of file
diff --git a/crates/biome_css_analyze/tests/specs/nursery/noDuplicateSelectors/invalid.css.snap.new b/crates/biome_css_analyze/tests/specs/nursery/noDuplicateSelectors/invalid.css.snap.new
new file mode 100644
index 00000000000..91a45dd9fa0
--- /dev/null
+++ b/crates/biome_css_analyze/tests/specs/nursery/noDuplicateSelectors/invalid.css.snap.new
@@ -0,0 +1,409 @@
+---
+source: crates/biome_css_analyze/tests/spec_tests.rs
+assertion_line: 83
+expression: invalid.css
+---
+# Input
+```css
+/* duplicate within one rule's selector list */
+a, a {}
+
+/* duplicate within one rule's selector list. multiline */
+b,
+b {}
+
+/* duplicate within one rule's selector list. multiline */
+c,
+d,
+d {}
+
+/* duplicated selectors within one rule's selector list. 2 duplicates */
+.e,
+.e,
+.e {}
+
+/* duplicate simple selectors with another rule between */
+f {} g {} f {}
+
+/* duplicate simple selectors with another rule between */
+h {}
+i {}
+h {}
+
+/* duplicate selector lists with different order */
+j, k {} k, j {}
+
+/* duplicate selectors with multiple components */
+m n {}
+m n {}
+
+/* essentially duplicate selector lists with varied spacing */
+.foo   p, q > .bar,
+#baz {}
+  #baz,
+  .foo     p,q>.bar {}
+
+/* duplicate within a media query, in the same rule */
+s {}
+@media print { s, s {} }
+
+/* duplicate within a media query, in different rules */
+t {}
+@media screen and (min-width: 900px) { t {} t {} }
+
+/* duplicate caused by nesting */
+v w {} v { w {} }
+
+/* duplicate caused by &-parent selector */
+x { & {} }
+```
+
+# Diagnostics
+```
+invalid.css:2:4 lint/nursery/noDuplicateSelectors ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  ! Duplicate selectors may result in unintentionally overriding rules: a
+  
+    1 │ /* duplicate within one rule's selector list */
+  > 2 │ a, a {}
+      │    ^
+    3 │ 
+    4 │ /* duplicate within one rule's selector list. multiline */
+  
+  i Please consider moving the rule's contents to the first occurence:
+  
+    1 │ /* duplicate within one rule's selector list */
+  > 2 │ a, a {}
+      │ ^
+    3 │ 
+    4 │ /* duplicate within one rule's selector list. multiline */
+  
+  i Remove duplicate selectors within the rule
+  
+
+```
+
+```
+invalid.css:6:1 lint/nursery/noDuplicateSelectors ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  ! Duplicate selectors may result in unintentionally overriding rules: b
+  
+    4 │ /* duplicate within one rule's selector list. multiline */
+    5 │ b,
+  > 6 │ b {}
+      │ ^
+    7 │ 
+    8 │ /* duplicate within one rule's selector list. multiline */
+  
+  i Please consider moving the rule's contents to the first occurence:
+  
+    4 │ /* duplicate within one rule's selector list. multiline */
+  > 5 │ b,
+      │ ^
+    6 │ b {}
+    7 │ 
+  
+  i Remove duplicate selectors within the rule
+  
+
+```
+
+```
+invalid.css:11:1 lint/nursery/noDuplicateSelectors ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  ! Duplicate selectors may result in unintentionally overriding rules: d
+  
+     9 │ c,
+    10 │ d,
+  > 11 │ d {}
+       │ ^
+    12 │ 
+    13 │ /* duplicated selectors within one rule's selector list. 2 duplicates */
+  
+  i Please consider moving the rule's contents to the first occurence:
+  
+     8 │ /* duplicate within one rule's selector list. multiline */
+     9 │ c,
+  > 10 │ d,
+       │ ^
+    11 │ d {}
+    12 │ 
+  
+  i Remove duplicate selectors within the rule
+  
+
+```
+
+```
+invalid.css:15:1 lint/nursery/noDuplicateSelectors ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  ! Duplicate selectors may result in unintentionally overriding rules: .e
+  
+    13 │ /* duplicated selectors within one rule's selector list. 2 duplicates */
+    14 │ .e,
+  > 15 │ .e,
+       │ ^^
+    16 │ .e {}
+    17 │ 
+  
+  i Please consider moving the rule's contents to the first occurence:
+  
+    13 │ /* duplicated selectors within one rule's selector list. 2 duplicates */
+  > 14 │ .e,
+       │ ^^
+    15 │ .e,
+    16 │ .e {}
+  
+  i Remove duplicate selectors within the rule
+  
+
+```
+
+```
+invalid.css:16:1 lint/nursery/noDuplicateSelectors ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  ! Duplicate selectors may result in unintentionally overriding rules: .e
+  
+    14 │ .e,
+    15 │ .e,
+  > 16 │ .e {}
+       │ ^^
+    17 │ 
+    18 │ /* duplicate simple selectors with another rule between */
+  
+  i Please consider moving the rule's contents to the first occurence:
+  
+    13 │ /* duplicated selectors within one rule's selector list. 2 duplicates */
+  > 14 │ .e,
+       │ ^^
+    15 │ .e,
+    16 │ .e {}
+  
+  i Remove duplicate selectors within the rule
+  
+
+```
+
+```
+invalid.css:19:11 lint/nursery/noDuplicateSelectors ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  ! Duplicate selectors may result in unintentionally overriding rules: f
+  
+    18 │ /* duplicate simple selectors with another rule between */
+  > 19 │ f {} g {} f {}
+       │           ^
+    20 │ 
+    21 │ /* duplicate simple selectors with another rule between */
+  
+  i Please consider moving the rule's contents to the first occurence:
+  
+    18 │ /* duplicate simple selectors with another rule between */
+  > 19 │ f {} g {} f {}
+       │ ^
+    20 │ 
+    21 │ /* duplicate simple selectors with another rule between */
+  
+  i Remove duplicate selectors within the rule
+  
+
+```
+
+```
+invalid.css:24:1 lint/nursery/noDuplicateSelectors ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  ! Duplicate selectors may result in unintentionally overriding rules: h
+  
+    22 │ h {}
+    23 │ i {}
+  > 24 │ h {}
+       │ ^
+    25 │ 
+    26 │ /* duplicate selector lists with different order */
+  
+  i Please consider moving the rule's contents to the first occurence:
+  
+    21 │ /* duplicate simple selectors with another rule between */
+  > 22 │ h {}
+       │ ^
+    23 │ i {}
+    24 │ h {}
+  
+  i Remove duplicate selectors within the rule
+  
+
+```
+
+```
+invalid.css:27:9 lint/nursery/noDuplicateSelectors ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  ! Duplicate selectors may result in unintentionally overriding rules: k, j
+  
+    26 │ /* duplicate selector lists with different order */
+  > 27 │ j, k {} k, j {}
+       │         ^^^^
+    28 │ 
+    29 │ /* duplicate selectors with multiple components */
+  
+  i Please consider moving the rule's contents to the first occurence:
+  
+    26 │ /* duplicate selector lists with different order */
+  > 27 │ j, k {} k, j {}
+       │ ^^^^
+    28 │ 
+    29 │ /* duplicate selectors with multiple components */
+  
+  i Remove duplicate selectors within the rule
+  
+
+```
+
+```
+invalid.css:31:1 lint/nursery/noDuplicateSelectors ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  ! Duplicate selectors may result in unintentionally overriding rules: m n
+  
+    29 │ /* duplicate selectors with multiple components */
+    30 │ m n {}
+  > 31 │ m n {}
+       │ ^^^
+    32 │ 
+    33 │ /* essentially duplicate selector lists with varied spacing */
+  
+  i Please consider moving the rule's contents to the first occurence:
+  
+    29 │ /* duplicate selectors with multiple components */
+  > 30 │ m n {}
+       │ ^^^
+    31 │ m n {}
+    32 │ 
+  
+  i Remove duplicate selectors within the rule
+  
+
+```
+
+```
+invalid.css:36:3 lint/nursery/noDuplicateSelectors ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  ! Duplicate selectors may result in unintentionally overriding rules: #baz,
+      .foo     p,q>.bar
+  
+    34 │ .foo   p, q > .bar,
+    35 │ #baz {}
+  > 36 │   #baz,
+       │   ^^^^^
+  > 37 │   .foo     p,q>.bar {}
+       │   ^^^^^^^^^^^^^^^^^
+    38 │ 
+    39 │ /* duplicate within a media query, in the same rule */
+  
+  i Please consider moving the rule's contents to the first occurence:
+  
+    33 │ /* essentially duplicate selector lists with varied spacing */
+  > 34 │ .foo   p, q > .bar,
+       │ ^^^^^^^^^^^^^^^^^^^
+  > 35 │ #baz {}
+       │ ^^^^
+    36 │   #baz,
+    37 │   .foo     p,q>.bar {}
+  
+  i Remove duplicate selectors within the rule
+  
+
+```
+
+```
+invalid.css:41:19 lint/nursery/noDuplicateSelectors ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  ! Duplicate selectors may result in unintentionally overriding rules: s
+  
+    39 │ /* duplicate within a media query, in the same rule */
+    40 │ s {}
+  > 41 │ @media print { s, s {} }
+       │                   ^
+    42 │ 
+    43 │ /* duplicate within a media query, in different rules */
+  
+  i Please consider moving the rule's contents to the first occurence:
+  
+    39 │ /* duplicate within a media query, in the same rule */
+    40 │ s {}
+  > 41 │ @media print { s, s {} }
+       │                ^
+    42 │ 
+    43 │ /* duplicate within a media query, in different rules */
+  
+  i Remove duplicate selectors within the rule
+  
+
+```
+
+```
+invalid.css:45:45 lint/nursery/noDuplicateSelectors ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  ! Duplicate selectors may result in unintentionally overriding rules: t
+  
+    43 │ /* duplicate within a media query, in different rules */
+    44 │ t {}
+  > 45 │ @media screen and (min-width: 900px) { t {} t {} }
+       │                                             ^
+    46 │ 
+    47 │ /* duplicate caused by nesting */
+  
+  i Please consider moving the rule's contents to the first occurence:
+  
+    43 │ /* duplicate within a media query, in different rules */
+    44 │ t {}
+  > 45 │ @media screen and (min-width: 900px) { t {} t {} }
+       │                                        ^
+    46 │ 
+    47 │ /* duplicate caused by nesting */
+  
+  i Remove duplicate selectors within the rule
+  
+
+```
+
+```
+invalid.css:48:12 lint/nursery/noDuplicateSelectors ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  ! Duplicate selectors may result in unintentionally overriding rules: w
+  
+    47 │ /* duplicate caused by nesting */
+  > 48 │ v w {} v { w {} }
+       │            ^
+    49 │ 
+    50 │ /* duplicate caused by &-parent selector */
+  
+  i Please consider moving the rule's contents to the first occurence:
+  
+    47 │ /* duplicate caused by nesting */
+  > 48 │ v w {} v { w {} }
+       │ ^^^
+    49 │ 
+    50 │ /* duplicate caused by &-parent selector */
+  
+  i Remove duplicate selectors within the rule
+  
+
+```
+
+```
+invalid.css:51:5 lint/nursery/noDuplicateSelectors ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  ! Duplicate selectors may result in unintentionally overriding rules: &
+  
+    50 │ /* duplicate caused by &-parent selector */
+  > 51 │ x { & {} }
+       │     ^
+  
+  i Please consider moving the rule's contents to the first occurence:
+  
+    50 │ /* duplicate caused by &-parent selector */
+  > 51 │ x { & {} }
+       │ ^
+  
+  i Remove duplicate selectors within the rule
+  
+
+```
diff --git a/crates/biome_css_analyze/tests/specs/nursery/noDuplicateSelectors/valid.css b/crates/biome_css_analyze/tests/specs/nursery/noDuplicateSelectors/valid.css
new file mode 100644
index 00000000000..51e77df7653
--- /dev/null
+++ b/crates/biome_css_analyze/tests/specs/nursery/noDuplicateSelectors/valid.css
@@ -0,0 +1,42 @@
+/* no duplicates */
+a {} b {} c {} d, e, f {}
+
+/* duplicate inside media query */
+g {}
+@media print { g {} }	
+
+/* duplicates inside separate media query */
+@media print {
+    gg.dev {}
+}
+@media print {
+    gg.dev {}
+}
+
+/* duplicate inside keyframes */
+@keyframes h { 0% {} }
+@keyframes h { 0% {} }
+
+/* duplicates inside nested rules */
+i { i { i {} } }
+
+/* selectors using parts of other selectors */
+.foo .bar {}
+.foo {}
+.bar {}
+.bar .foo {}
+
+/* selectors reused in other non-equivalent selector lists */
+j {} j, k {}
+u {} v, u {}
+
+/* nested resolution */
+m n { top: 0; } m { n, p { color: pink; } }	
+
+@mixin abc { &:hover {} } @mixin xyz { &:hover {} }
+
+/* pass if default setting i.e. disallowInList: false */
+ul, ol {} ul {}
+
+/* attribute selector */
+[disabled].goo, [disabled] .goo {}
\ No newline at end of file
diff --git a/crates/biome_css_analyze/tests/specs/nursery/noDuplicateSelectors/valid.css.snap.new b/crates/biome_css_analyze/tests/specs/nursery/noDuplicateSelectors/valid.css.snap.new
new file mode 100644
index 00000000000..6b02fb5775b
--- /dev/null
+++ b/crates/biome_css_analyze/tests/specs/nursery/noDuplicateSelectors/valid.css.snap.new
@@ -0,0 +1,50 @@
+---
+source: crates/biome_css_analyze/tests/spec_tests.rs
+assertion_line: 83
+expression: valid.css
+---
+# Input
+```css
+/* no duplicates */
+a {} b {} c {} d, e, f {}
+
+/* duplicate inside media query */
+g {}
+@media print { g {} }	
+
+/* duplicates inside separate media query */
+@media print {
+    gg.dev {}
+}
+@media print {
+    gg.dev {}
+}
+
+/* duplicate inside keyframes */
+@keyframes h { 0% {} }
+@keyframes h { 0% {} }
+
+/* duplicates inside nested rules */
+i { i { i {} } }
+
+/* selectors using parts of other selectors */
+.foo .bar {}
+.foo {}
+.bar {}
+.bar .foo {}
+
+/* selectors reused in other non-equivalent selector lists */
+j {} j, k {}
+u {} v, u {}
+
+/* nested resolution */
+m n { top: 0; } m { n, p { color: pink; } }	
+
+@mixin abc { &:hover {} } @mixin xyz { &:hover {} }
+
+/* pass if default setting i.e. disallowInList: false */
+ul, ol {} ul {}
+
+/* attribute selector */
+[disabled].goo, [disabled] .goo {}
+```
diff --git a/crates/biome_diagnostics_categories/src/categories.rs b/crates/biome_diagnostics_categories/src/categories.rs
index 2eaa80a08ca..343c113f646 100644
--- a/crates/biome_diagnostics_categories/src/categories.rs
+++ b/crates/biome_diagnostics_categories/src/categories.rs
@@ -119,6 +119,7 @@ define_categories! {
     "lint/nursery/noDuplicateElseIf": "https://biomejs.dev/linter/rules/no-duplicate-else-if",
     "lint/nursery/noDuplicateFontNames": "https://biomejs.dev/linter/rules/no-font-family-duplicate-names",
     "lint/nursery/noDuplicateJsonKeys": "https://biomejs.dev/linter/rules/no-duplicate-json-keys",
+    "lint/nursery/noDuplicateSelectors": "https://biomejs.dev/linter/rules/no-duplicate-selectors",
     "lint/nursery/noDuplicateSelectorsKeyframeBlock": "https://biomejs.dev/linter/rules/no-duplicate-selectors-keyframe-block",
     "lint/nursery/noEvolvingAny": "https://biomejs.dev/linter/rules/no-evolving-any",
     "lint/nursery/noFlatMapIdentity": "https://biomejs.dev/linter/rules/no-flat-map-identity",
diff --git a/packages/@biomejs/backend-jsonrpc/src/workspace.ts b/packages/@biomejs/backend-jsonrpc/src/workspace.ts
index 9e6b5dfa725..da9ba8684f1 100644
--- a/packages/@biomejs/backend-jsonrpc/src/workspace.ts
+++ b/packages/@biomejs/backend-jsonrpc/src/workspace.ts
@@ -944,6 +944,10 @@ export interface Nursery {
 	 * Disallow two keys with the same name inside a JSON object.
 	 */
 	noDuplicateJsonKeys?: RuleConfiguration_for_Null;
+	/**
+	 * Disallow duplicate selectors. This rule checks for two types of duplication:
+	 */
+	noDuplicateSelectors?: RuleConfiguration_for_NoDuplicateSelectorsOptions;
 	/**
 	 * Disallow duplicate selectors within keyframe blocks.
 	 */
@@ -1582,6 +1586,9 @@ export type RuleConfiguration_for_DeprecatedHooksOptions =
 export type RuleConfiguration_for_NoCssEmptyBlockOptions =
 	| RulePlainConfiguration
 	| RuleWithOptions_for_NoCssEmptyBlockOptions;
+export type RuleConfiguration_for_NoDuplicateSelectorsOptions =
+	| RulePlainConfiguration
+	| RuleWithOptions_for_NoDuplicateSelectorsOptions;
 export type RuleConfiguration_for_RestrictedImportsOptions =
 	| RulePlainConfiguration
 	| RuleWithOptions_for_RestrictedImportsOptions;
@@ -1625,6 +1632,10 @@ export interface RuleWithOptions_for_NoCssEmptyBlockOptions {
 	level: RulePlainConfiguration;
 	options: NoCssEmptyBlockOptions;
 }
+export interface RuleWithOptions_for_NoDuplicateSelectorsOptions {
+	level: RulePlainConfiguration;
+	options: NoDuplicateSelectorsOptions;
+}
 export interface RuleWithOptions_for_RestrictedImportsOptions {
 	level: RulePlainConfiguration;
 	options: RestrictedImportsOptions;
@@ -1678,6 +1689,12 @@ export interface DeprecatedHooksOptions {}
 export interface NoCssEmptyBlockOptions {
 	allowComments: boolean;
 }
+export interface NoDuplicateSelectorsOptions {
+	/**
+	 * If set to `true` this rule will check for duplicate selectors within selector lists.
+	 */
+	disallowInList: boolean;
+}
 /**
  * Options for the rule `noRestrictedImports`.
  */
@@ -2018,6 +2035,7 @@ export type Category =
 	| "lint/nursery/noDuplicateElseIf"
 	| "lint/nursery/noDuplicateFontNames"
 	| "lint/nursery/noDuplicateJsonKeys"
+	| "lint/nursery/noDuplicateSelectors"
 	| "lint/nursery/noDuplicateSelectorsKeyframeBlock"
 	| "lint/nursery/noEvolvingAny"
 	| "lint/nursery/noFlatMapIdentity"
diff --git a/packages/@biomejs/biome/configuration_schema.json b/packages/@biomejs/biome/configuration_schema.json
index 7078e0ec756..72325bf775f 100644
--- a/packages/@biomejs/biome/configuration_schema.json
+++ b/packages/@biomejs/biome/configuration_schema.json
@@ -1425,6 +1425,23 @@
 			"properties": { "allowComments": { "type": "boolean" } },
 			"additionalProperties": false
 		},
+		"NoDuplicateSelectorsConfiguration": {
+			"anyOf": [
+				{ "$ref": "#/definitions/RulePlainConfiguration" },
+				{ "$ref": "#/definitions/RuleWithNoDuplicateSelectorsOptions" }
+			]
+		},
+		"NoDuplicateSelectorsOptions": {
+			"type": "object",
+			"required": ["disallowInList"],
+			"properties": {
+				"disallowInList": {
+					"description": "If set to `true` this rule will check for duplicate selectors within selector lists.",
+					"type": "boolean"
+				}
+			},
+			"additionalProperties": false
+		},
 		"Nursery": {
 			"description": "A list of rules that belong to this group",
 			"type": "object",
@@ -1496,6 +1513,13 @@
 						{ "type": "null" }
 					]
 				},
+				"noDuplicateSelectors": {
+					"description": "Disallow duplicate selectors. This rule checks for two types of duplication:",
+					"anyOf": [
+						{ "$ref": "#/definitions/NoDuplicateSelectorsConfiguration" },
+						{ "type": "null" }
+					]
+				},
 				"noDuplicateSelectorsKeyframeBlock": {
 					"description": "Disallow duplicate selectors within keyframe blocks.",
 					"anyOf": [
@@ -1980,6 +2004,15 @@
 			},
 			"additionalProperties": false
 		},
+		"RuleWithNoDuplicateSelectorsOptions": {
+			"type": "object",
+			"required": ["level", "options"],
+			"properties": {
+				"level": { "$ref": "#/definitions/RulePlainConfiguration" },
+				"options": { "$ref": "#/definitions/NoDuplicateSelectorsOptions" }
+			},
+			"additionalProperties": false
+		},
 		"RuleWithNoOptions": {
 			"type": "object",
 			"required": ["level"],