diff --git a/.changeset/many-mugs-camp.md b/.changeset/many-mugs-camp.md
new file mode 100644
index 0000000000..61e350203d
--- /dev/null
+++ b/.changeset/many-mugs-camp.md
@@ -0,0 +1,5 @@
+---
+"stylelint": minor
+---
+
+Fixed: `selector-pseudo-class-no-unknown` false positive for `:modal`
diff --git a/lib/reference/selectors.js b/lib/reference/selectors.js
index 69ff5892ff..5acfb77182 100644
--- a/lib/reference/selectors.js
+++ b/lib/reference/selectors.js
@@ -277,6 +277,7 @@ const pseudoClasses = uniteSets(
 		'last-child',
 		'last-of-type',
 		'link',
+		'modal',
 		'only-child',
 		'only-of-type',
 		'optional',
diff --git a/lib/rules/selector-pseudo-class-no-unknown/__tests__/index.js b/lib/rules/selector-pseudo-class-no-unknown/__tests__/index.js
index 1874a48225..54dc317bae 100644
--- a/lib/rules/selector-pseudo-class-no-unknown/__tests__/index.js
+++ b/lib/rules/selector-pseudo-class-no-unknown/__tests__/index.js
@@ -28,6 +28,9 @@ testRule({
 		{
 			code: 'a::before { }',
 		},
+		{
+			code: ':modal { }',
+		},
 		{
 			code: "input:not([type='submit']) { }",
 		},