diff --git a/.changeset/grumpy-monkeys-tap.md b/.changeset/grumpy-monkeys-tap.md
new file mode 100644
index 000000000000..dd2a3fbf444b
--- /dev/null
+++ b/.changeset/grumpy-monkeys-tap.md
@@ -0,0 +1,5 @@
+---
+"@biomejs/biome": patch
+---
+
+Fixed [#7301](https://github.com/biomejs/biome/issues/7301): [`useReadonlyClassProperties`](https://biomejs.dev/linter/rules/use-readonly-class-properties/) now correctly skips JavaScript files.
diff --git a/crates/biome_js_analyze/src/lint/style/use_readonly_class_properties.rs b/crates/biome_js_analyze/src/lint/style/use_readonly_class_properties.rs
index 86ee5c45ab75..34f26bc557de 100644
--- a/crates/biome_js_analyze/src/lint/style/use_readonly_class_properties.rs
+++ b/crates/biome_js_analyze/src/lint/style/use_readonly_class_properties.rs
@@ -10,8 +10,8 @@ use biome_js_syntax::{
     JsArrowFunctionExpression, JsAssignmentExpression, JsAwaitExpression, JsBlockStatement,
     JsCallArgumentList, JsCallArguments, JsCallExpression, JsClassDeclaration, JsClassMemberList,
     JsConditionalExpression, JsConstructorClassMember, JsElseClause, JsExpressionStatement,
-    JsFunctionBody, JsFunctionExpression, JsGetterClassMember, JsGetterObjectMember, JsIfStatement,
-    JsInitializerClause, JsLanguage, JsMethodClassMember, JsMethodObjectMember,
+    JsFileSource, JsFunctionBody, JsFunctionExpression, JsGetterClassMember, JsGetterObjectMember,
+    JsIfStatement, JsInitializerClause, JsLanguage, JsMethodClassMember, JsMethodObjectMember,
     JsObjectAssignmentPattern, JsObjectExpression, JsObjectMemberList, JsParenthesizedExpression,
     JsPostUpdateExpression, JsPreUpdateExpression, JsPropertyClassMember, JsReturnStatement,
     JsSetterClassMember, JsSetterObjectMember, JsStatementList, JsStaticMemberAssignment,
@@ -139,6 +139,11 @@ impl Rule for UseReadonlyClassProperties {
     type Options = UseReadonlyClassPropertiesOptions;
 
     fn run(ctx: &RuleContext<Self>) -> Self::Signals {
+        let source_type = ctx.source_type::<JsFileSource>().language();
+        if !source_type.is_typescript() {
+            return Box::default();
+        }
+
         let root = ctx.query();
         let members = root.members();
         let private_only = !ctx.options().check_all_properties;
diff --git a/crates/biome_js_analyze/tests/specs/style/useReadonlyClassProperties/valid.js b/crates/biome_js_analyze/tests/specs/style/useReadonlyClassProperties/valid.js
new file mode 100644
index 000000000000..b6fc027f1f69
--- /dev/null
+++ b/crates/biome_js_analyze/tests/specs/style/useReadonlyClassProperties/valid.js
@@ -0,0 +1,7 @@
+// should not generate diagnostics
+
+// should skip because of JavaScript
+class MyClass {
+	foo = 34;
+	#bar = 33;
+}
diff --git a/crates/biome_js_analyze/tests/specs/style/useReadonlyClassProperties/valid.js.snap b/crates/biome_js_analyze/tests/specs/style/useReadonlyClassProperties/valid.js.snap
new file mode 100644
index 000000000000..533337cec364
--- /dev/null
+++ b/crates/biome_js_analyze/tests/specs/style/useReadonlyClassProperties/valid.js.snap
@@ -0,0 +1,15 @@
+---
+source: crates/biome_js_analyze/tests/spec_tests.rs
+expression: valid.js
+---
+# Input
+```js
+// should not generate diagnostics
+
+// should skip because of JavaScript
+class MyClass {
+	foo = 34;
+	#bar = 33;
+}
+
+```