diff --git a/changelog/fix_an_incorrect_autocorrect_for_style_map_compact_with_conditional_block.md b/changelog/fix_an_incorrect_autocorrect_for_style_map_compact_with_conditional_block.md
new file mode 100644
index 000000000000..95221870820d
--- /dev/null
+++ b/changelog/fix_an_incorrect_autocorrect_for_style_map_compact_with_conditional_block.md
@@ -0,0 +1 @@
+* [#12683](https://github.com/rubocop/rubocop/issues/12683): Fix an incorrect autocorrect for `Style/MapCompactWithConditionalBlock` when using guard clause with `next` implicitly nil. ([@koic][])
diff --git a/lib/rubocop/cop/style/map_compact_with_conditional_block.rb b/lib/rubocop/cop/style/map_compact_with_conditional_block.rb
index 24b85f91e521..d880fbca7731 100644
--- a/lib/rubocop/cop/style/map_compact_with_conditional_block.rb
+++ b/lib/rubocop/cop/style/map_compact_with_conditional_block.rb
@@ -116,10 +116,10 @@ def truthy_branch_for_if?(node)
         def truthy_branch_for_guard?(node)
           if_node = node.left_sibling
 
-          if if_node.if? || if_node.ternary?
-            if_node.else_branch.nil?
-          elsif if_node.unless?
-            if_node.if_branch.nil?
+          if if_node.if?
+            if_node.if_branch.arguments.any?
+          else
+            if_node.if_branch.arguments.none?
           end
         end
 
diff --git a/spec/rubocop/cop/style/map_compact_with_conditional_block_spec.rb b/spec/rubocop/cop/style/map_compact_with_conditional_block_spec.rb
index 0ce0b54c283e..76404fa6fb47 100644
--- a/spec/rubocop/cop/style/map_compact_with_conditional_block_spec.rb
+++ b/spec/rubocop/cop/style/map_compact_with_conditional_block_spec.rb
@@ -158,10 +158,10 @@
       RUBY
     end
 
-    it 'registers an offense and corrects to `select` with guard clause of `if`' do
+    it 'registers an offense and corrects to `reject` with guard clause of `if`' do
       expect_offense(<<~RUBY)
         foo.map do |item|
-            ^^^^^^^^^^^^^ Replace `map { ... }.compact` with `select`.
+            ^^^^^^^^^^^^^ Replace `map { ... }.compact` with `reject`.
           next if item.bar?
 
           item
@@ -169,14 +169,14 @@
       RUBY
 
       expect_correction <<~RUBY
-        foo.select { |item| item.bar? }
+        foo.reject { |item| item.bar? }
       RUBY
     end
 
-    it 'registers an offense and corrects to `reject` with guard clause of `unless`' do
+    it 'registers an offense and corrects to `select` with guard clause of `unless`' do
       expect_offense(<<~RUBY)
         foo.map do |item|
-            ^^^^^^^^^^^^^ Replace `map { ... }.compact` with `reject`.
+            ^^^^^^^^^^^^^ Replace `map { ... }.compact` with `select`.
           next unless item.bar?
 
           item
@@ -184,7 +184,7 @@
       RUBY
 
       expect_correction <<~RUBY
-        foo.reject { |item| item.bar? }
+        foo.select { |item| item.bar? }
       RUBY
     end