diff --git a/packages/eslint-plugin/src/rules/consistent-indexed-object-style.ts b/packages/eslint-plugin/src/rules/consistent-indexed-object-style.ts
index 3da9692df9e..e4e73d89752 100644
--- a/packages/eslint-plugin/src/rules/consistent-indexed-object-style.ts
+++ b/packages/eslint-plugin/src/rules/consistent-indexed-object-style.ts
@@ -132,7 +132,7 @@ export default createRule<Options, MessageIds>({
 
           if ((node.typeParameters?.params ?? []).length > 0) {
             genericTypes = `<${node.typeParameters?.params
-              .map(p => p.name.name)
+              .map(p => sourceCode.getText(p))
               .join(', ')}>`;
           }
 
diff --git a/packages/eslint-plugin/tests/rules/consistent-indexed-object-style.test.ts b/packages/eslint-plugin/tests/rules/consistent-indexed-object-style.test.ts
index 9c92f1a2eac..b02fd3dfa2d 100644
--- a/packages/eslint-plugin/tests/rules/consistent-indexed-object-style.test.ts
+++ b/packages/eslint-plugin/tests/rules/consistent-indexed-object-style.test.ts
@@ -174,6 +174,19 @@ type Foo<A> = Record<string, A>;
       errors: [{ messageId: 'preferRecord', line: 2, column: 1 }],
     },
 
+    // Interface with generic parameter and default value
+    {
+      code: `
+interface Foo<A = any> {
+  [key: string]: A;
+}
+      `,
+      output: `
+type Foo<A = any> = Record<string, A>;
+      `,
+      errors: [{ messageId: 'preferRecord', line: 2, column: 1 }],
+    },
+
     // Interface with extends
     {
       code: `