diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index dcfd299..1e9fe2f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -55,7 +55,7 @@ jobs:
                   CI: true
 
     test_types:
-        name: Test Types (core)
+        name: Test Types
         runs-on: ubuntu-latest
         steps:
             - uses: actions/checkout@v4
@@ -65,13 +65,20 @@ jobs:
               with:
                   node-version: "lts/*"
 
-            - name: npm install and test types
+            - name: npm install and test types (core)
               working-directory: packages/core
               run: |
                   npm install
                   npm run build
                   npm run test:types
 
+            - name: npm install and test types (plugin-kit)
+              working-directory: packages/plugin-kit
+              run: |
+                  npm install
+                  npm run build
+                  npm run test:types
+
     jsr_test:
         name: Verify JSR Publish
         runs-on: ubuntu-latest
diff --git a/packages/core/tests/types/cjs-import.test.cts b/packages/core/tests/types/cjs-import.test.cts
new file mode 100644
index 0000000..2fe5e2b
--- /dev/null
+++ b/packages/core/tests/types/cjs-import.test.cts
@@ -0,0 +1,10 @@
+/**
+ * @fileoverview CommonJS type import test for ESLint Core.
+ * @author Francesco Trotta
+ */
+
+//-----------------------------------------------------------------------------
+// Imports
+//-----------------------------------------------------------------------------
+
+import "@eslint/core";
diff --git a/packages/core/tests/types/tsconfig.json b/packages/core/tests/types/tsconfig.json
index 7bbf5d8..b3220a7 100644
--- a/packages/core/tests/types/tsconfig.json
+++ b/packages/core/tests/types/tsconfig.json
@@ -5,5 +5,5 @@
     "rootDir": "../..",
     "strict": true
   },
-  "files": ["../../dist/esm/types.d.ts", "types.test.ts"]
+  "include": [".", "../../dist"]
 }
diff --git a/packages/plugin-kit/build-cts.js b/packages/plugin-kit/build-cts.js
new file mode 100644
index 0000000..ade7ae1
--- /dev/null
+++ b/packages/plugin-kit/build-cts.js
@@ -0,0 +1,16 @@
+/**
+ * @fileoverview Rewrites import expressions for CommonJS compatibility.
+ * This script creates "dist/cjs/index.d.cts" from "dist/esm/index.d.ts" by modifying imports
+ * from `"./types.ts"` to `"./types.cts"`.
+ *
+ * @author Francesco Trotta
+ */
+
+import { readFile, writeFile } from "node:fs/promises";
+
+const oldSourceText = await readFile("dist/esm/index.d.ts", "utf-8");
+const newSourceText = oldSourceText.replaceAll(
+	'import("./types.ts")',
+	'import("./types.cts")',
+);
+await writeFile("dist/cjs/index.d.cts", newSourceText);
diff --git a/packages/plugin-kit/package.json b/packages/plugin-kit/package.json
index 8113a4f..ebe694e 100644
--- a/packages/plugin-kit/package.json
+++ b/packages/plugin-kit/package.json
@@ -32,12 +32,13 @@
   "homepage": "https://github.com/eslint/rewrite#readme",
   "scripts": {
     "build:dedupe-types": "node ../../tools/dedupe-types.js dist/cjs/index.cjs dist/esm/index.js",
-    "build:cts": "node -e \"fs.copyFileSync('dist/esm/index.d.ts', 'dist/cjs/index.d.cts')\"",
+    "build:cts": "node ./build-cts.js",
     "build": "rollup -c && npm run build:dedupe-types && tsc -p tsconfig.esm.json && npm run build:cts",
-    "test:jsr": "npx jsr@latest publish --dry-run",
     "pretest": "npm run build",
     "test": "mocha tests/",
-    "test:coverage": "c8 npm test"
+    "test:coverage": "c8 npm test",
+    "test:jsr": "npx jsr@latest publish --dry-run",
+    "test:types": "tsc -p tests/types/tsconfig.json"
   },
   "keywords": [
     "eslint",
@@ -45,8 +46,11 @@
     "eslint-plugin"
   ],
   "license": "Apache-2.0",
-  "devDependencies": {
+  "dependencies": {
     "@eslint/core": "^0.9.1",
+    "levn": "^0.4.1"
+  },
+  "devDependencies": {
     "@types/levn": "^0.4.0",
     "c8": "^9.1.0",
     "mocha": "^10.4.0",
@@ -56,8 +60,5 @@
   },
   "engines": {
     "node": "^18.18.0 || ^20.9.0 || >=21.1.0"
-  },
-  "dependencies": {
-    "levn": "^0.4.1"
   }
 }
diff --git a/packages/plugin-kit/rollup.config.js b/packages/plugin-kit/rollup.config.js
index 03a11e1..5b813a8 100644
--- a/packages/plugin-kit/rollup.config.js
+++ b/packages/plugin-kit/rollup.config.js
@@ -16,7 +16,7 @@ export default {
 	plugins: [
 		copy({
 			targets: [
-				{ src: "src/types.ts", dest: "dist/cjs" },
+				{ src: "src/types.ts", dest: "dist/cjs", rename: "types.cts" },
 				{ src: "src/types.ts", dest: "dist/esm" },
 			],
 		}),
diff --git a/packages/plugin-kit/tests/types/cjs-import.test.cts b/packages/plugin-kit/tests/types/cjs-import.test.cts
new file mode 100644
index 0000000..98a6ed1
--- /dev/null
+++ b/packages/plugin-kit/tests/types/cjs-import.test.cts
@@ -0,0 +1,10 @@
+/**
+ * @fileoverview CommonJS type import test for ESLint Plugin Kit.
+ * @author Francesco Trotta
+ */
+
+//-----------------------------------------------------------------------------
+// Imports
+//-----------------------------------------------------------------------------
+
+import "@eslint/plugin-kit";
diff --git a/packages/plugin-kit/tests/types/tsconfig.json b/packages/plugin-kit/tests/types/tsconfig.json
new file mode 100644
index 0000000..b3220a7
--- /dev/null
+++ b/packages/plugin-kit/tests/types/tsconfig.json
@@ -0,0 +1,9 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "noEmit": true,
+    "rootDir": "../..",
+    "strict": true
+  },
+  "include": [".", "../../dist"]
+}
diff --git a/packages/plugin-kit/tests/types/types.test.ts b/packages/plugin-kit/tests/types/types.test.ts
new file mode 100644
index 0000000..6643887
--- /dev/null
+++ b/packages/plugin-kit/tests/types/types.test.ts
@@ -0,0 +1,104 @@
+/**
+ * @fileoverview Type tests for ESLint Plugin Kit.
+ * @author Francesco Trotta
+ */
+
+//-----------------------------------------------------------------------------
+// Imports
+//-----------------------------------------------------------------------------
+
+import {
+	BooleanConfig,
+	CallMethodStep,
+	ConfigCommentParser,
+	Directive,
+	DirectiveType,
+	RulesConfig,
+	SourceLocation,
+	SourceRange,
+	StringConfig,
+	TextSourceCodeBase,
+	VisitNodeStep,
+} from "@eslint/plugin-kit";
+
+//-----------------------------------------------------------------------------
+// Tests
+//-----------------------------------------------------------------------------
+
+// CallMethodStep
+class TestCallMethodStep extends CallMethodStep {
+	constructor({ target, args }: { target: string; args: [string, number] }) {
+		super({ target, args });
+	}
+}
+const step2 = new TestCallMethodStep({ target: "foo", args: ["foo", 42] });
+step2.args satisfies unknown[];
+step2.kind satisfies 2;
+step2.target satisfies string;
+step2.type satisfies "call";
+
+// ConfigCommentParser
+const configCommentParser = new ConfigCommentParser();
+configCommentParser.parseDirective("foo") satisfies
+	| { label: string; value: string; justification: string }
+	| undefined;
+const jsonLikeConfig = configCommentParser.parseJSONLikeConfig("bar");
+if (jsonLikeConfig.ok) {
+	jsonLikeConfig.config satisfies RulesConfig;
+} else {
+	jsonLikeConfig.error.message satisfies string;
+}
+configCommentParser.parseListConfig("baz") satisfies BooleanConfig;
+configCommentParser.parseStringConfig("qux") satisfies StringConfig;
+
+// Directive
+void ((type: "disable" | "enable" | "disable-next-line" | "disable-line") => {
+	const directive = new Directive({
+		type,
+		node: {},
+		value: "foo",
+		justification: "bar",
+	});
+	directive.justification satisfies string;
+	directive.node satisfies unknown;
+	directive.type satisfies DirectiveType;
+	directive.value satisfies string;
+});
+
+// TextSourceCodeBase
+class TestTextSourceCode extends TextSourceCodeBase {
+	declare ast: { foo: string; bar: number };
+	constructor({
+		text,
+		ast,
+	}: {
+		text: string;
+		ast: { foo: string; bar: number };
+	}) {
+		super({ text, ast, lineEndingPattern: /\r\n|[\r\n\u2028\u2029]/u });
+	}
+}
+const sourceCode = new TestTextSourceCode({
+	text: "text",
+	ast: { foo: "ABC", bar: 123 },
+});
+sourceCode.ast satisfies { foo: string; bar: number };
+sourceCode.getAncestors({}) satisfies object[];
+sourceCode.getLoc({}) satisfies SourceLocation;
+sourceCode.getParent({}) satisfies object | undefined;
+sourceCode.getRange({}) satisfies SourceRange;
+sourceCode.getText() satisfies string;
+sourceCode.getText({}, 0, 1) satisfies string;
+
+// VisitNodeStep
+class TestVisitNodeStep extends VisitNodeStep {
+	constructor({ target, phase }: { target: object; phase: 1 | 2 }) {
+		super({ target, phase, args: ["foo", 42] });
+	}
+}
+const step1 = new TestVisitNodeStep({ target: { foo: "bar" }, phase: 2 });
+step1.args satisfies unknown[];
+step1.kind satisfies 1;
+step1.phase satisfies 1 | 2;
+step1.target satisfies object;
+step1.type satisfies "visit";