diff --git a/packages/rstack/src/rslintConfig.ts b/packages/rstack/src/rslintConfig.ts
index c221f359..44062819 100644
--- a/packages/rstack/src/rslintConfig.ts
+++ b/packages/rstack/src/rslintConfig.ts
@@ -29,13 +29,16 @@ const resolvedLintConfig: RslintConfig = lintEntries.map((entry) => ({
   ...entry,
 }));
 
-const hasExplicitProject = lintEntries.some(
-  (entry) => entry.languageOptions?.parserOptions?.project !== undefined,
-);
+const hasExplicitProjectMode = lintEntries.some((entry) => {
+  const options = entry.languageOptions?.parserOptions;
+  return (
+    options?.project !== undefined || options?.projectService !== undefined
+  );
+});
 
 // Rslint's implicit tsconfig lookup also follows the internal config directory.
-// Preserve the CWD lookup without overriding user projects.
-if (!hasExplicitProject && existsSync(join(basePath, 'tsconfig.json'))) {
+// Preserve the CWD lookup only when neither project option is explicitly set.
+if (!hasExplicitProjectMode && existsSync(join(basePath, 'tsconfig.json'))) {
   resolvedLintConfig.push({
     basePath,
     languageOptions: {
diff --git a/packages/rstack/tests/cli/check.test.ts b/packages/rstack/tests/cli/check.test.ts
index bf368fad..a89b360f 100644
--- a/packages/rstack/tests/cli/check.test.ts
+++ b/packages/rstack/tests/cli/check.test.ts
@@ -168,6 +168,40 @@ test('enables type checking only with --type-check', () => {
   expect(withTypeCheck.stdout).toContain('Format check passed in');
 });
 
+test.each([true, false])(
+  'respects explicit projectService: %s with a root tsconfig',
+  (projectService) => {
+    writeProjectFile(
+      'rstack.config.ts',
+      `import { define } from 'rstack';
+
+define.lint([
+  {
+    files: ['**/*.ts'],
+    languageOptions: {
+      parserOptions: { projectService: ${projectService} },
+    },
+    rules: { 'no-debugger': 'error' },
+  },
+]);
+`,
+    );
+    writeProjectFile('tsconfig.json', '{"include":["src"]}\n');
+    writeProjectFile('src/index.ts', 'const value: string = 1;\n');
+
+    const result = runCheck(['--type-check', 'src/index.ts']);
+
+    expect(result.status).toBe(projectService ? 1 : 0);
+    const output = `${result.stdout}\n${result.stderr}`;
+    if (projectService) {
+      expect(output).toContain('TS2322');
+    } else {
+      expect(output).not.toContain('TS2322');
+    }
+    expect(result.stdout).toContain('Format check passed in');
+  },
+);
+
 test.each([
   { source: 'debugger;\n', formatted: true },
   { source: 'debugger;const value=true', formatted: false },