diff --git a/packages/router/src/ValidSignature.php b/packages/router/src/ValidSignature.php
new file mode 100644
index 000000000..e624d06c4
--- /dev/null
+++ b/packages/router/src/ValidSignature.php
@@ -0,0 +1,43 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tempest\Router;
+
+use Attribute;
+
+/**
+ * Validates that the request has a valid signature.
+ *
+ * This attribute should be used on routes that require a signed URL.
+ * If the signature is invalid or missing, a 403 Forbidden response is returned.
+ * If the signature has expired (for temporary signed URLs), a 403 Forbidden response is also returned.
+ *
+ * Usage:
+ * ```php
+ * #[Get('/verify-email')]
+ * #[ValidSignature]
+ * public function verifyEmail(string $token): Response
+ * {
+ *     // This code only executes if the signature is valid
+ * }
+ * ```
+ *
+ * @see UriGenerator::createSignedUri()
+ * @see UriGenerator::createTemporarySignedUri()
+ */
+#[Attribute(Attribute::TARGET_METHOD | Attribute::TARGET_CLASS)]
+final class ValidSignature implements RouteDecorator
+{
+    public function decorate(Route $route): Route
+    {
+        // ValidSignatureMiddleware uses #[SkipDiscovery] to prevent auto-discovery
+        // as a global middleware. It is only applied to routes with this attribute.
+        $route->middleware = [
+            ...$route->middleware,
+            ValidSignatureMiddleware::class,
+        ];
+
+        return $route;
+    }
+}
diff --git a/packages/router/src/ValidSignatureMiddleware.php b/packages/router/src/ValidSignatureMiddleware.php
new file mode 100644
index 000000000..1e1a7d5e1
--- /dev/null
+++ b/packages/router/src/ValidSignatureMiddleware.php
@@ -0,0 +1,38 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tempest\Router;
+
+use Tempest\Discovery\SkipDiscovery;
+use Tempest\Http\Request;
+use Tempest\Http\Response;
+use Tempest\Http\Responses\Forbidden;
+
+/**
+ * Middleware that validates the signature of a signed URL.
+ *
+ * Returns 403 Forbidden if:
+ * - The signature is missing
+ * - The signature is invalid (tampered URL)
+ * - The signature has expired (for temporary signed URLs)
+ *
+ * This middleware uses #[SkipDiscovery] to prevent auto-registration as a global middleware.
+ * It should only run on routes that have the #[ValidSignature] attribute.
+ */
+#[SkipDiscovery]
+final readonly class ValidSignatureMiddleware implements HttpMiddleware
+{
+    public function __construct(
+        private UriGenerator $uriGenerator,
+    ) {}
+
+    public function __invoke(Request $request, HttpMiddlewareCallable $next): Response
+    {
+        if (! $this->uriGenerator->hasValidSignature($request)) {
+            return new Forbidden();
+        }
+
+        return $next($request);
+    }
+}
diff --git a/tests/Integration/Route/Fixtures/SignedUrlController.php b/tests/Integration/Route/Fixtures/SignedUrlController.php
new file mode 100644
index 000000000..79e93b146
--- /dev/null
+++ b/tests/Integration/Route/Fixtures/SignedUrlController.php
@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Tempest\Integration\Route\Fixtures;
+
+use Tempest\Http\Response;
+use Tempest\Http\Responses\Ok;
+use Tempest\Router\Get;
+use Tempest\Router\ValidSignature;
+
+final readonly class SignedUrlController
+{
+    #[Get('/signed-action/{token}')]
+    #[ValidSignature]
+    public function signedAction(string $token): Response
+    {
+        return new Ok(['token' => $token, 'message' => 'Signature valid']);
+    }
+
+    #[Get('/unsigned-action/{token}')]
+    public function unsignedAction(string $token): Response
+    {
+        return new Ok(['token' => $token]);
+    }
+}
diff --git a/tests/Integration/Route/ValidSignatureMiddlewareTest.php b/tests/Integration/Route/ValidSignatureMiddlewareTest.php
new file mode 100644
index 000000000..7bcc69c1b
--- /dev/null
+++ b/tests/Integration/Route/ValidSignatureMiddlewareTest.php
@@ -0,0 +1,154 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\Tempest\Integration\Route;
+
+use PHPUnit\Framework\Attributes\Test;
+use Tempest\DateTime\Duration;
+use Tempest\Http\Status;
+use Tempest\Router\UriGenerator;
+use Tests\Tempest\Integration\FrameworkIntegrationTestCase;
+use Tests\Tempest\Integration\Route\Fixtures\SignedUrlController;
+
+final class ValidSignatureMiddlewareTest extends FrameworkIntegrationTestCase
+{
+    private UriGenerator $generator {
+        get => $this->container->get(UriGenerator::class);
+    }
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $this->http->registerRoute([SignedUrlController::class, 'signedAction']);
+        $this->http->registerRoute([SignedUrlController::class, 'unsignedAction']);
+    }
+
+    #[Test]
+    public function valid_signature_allows_request(): void
+    {
+        $uri = $this->generator->createSignedUri(
+            action: [SignedUrlController::class, 'signedAction'],
+            token: 'abc123',
+        );
+
+        $response = $this->http->get($uri);
+
+        $this->assertSame(Status::OK, $response->status);
+        $body = is_array($response->body) ? $response->body : json_decode($response->body, true);
+        $this->assertSame('abc123', $body['token']);
+        $this->assertSame('Signature valid', $body['message']);
+    }
+
+    #[Test]
+    public function missing_signature_returns_forbidden(): void
+    {
+        $response = $this->http->get('/signed-action/abc123');
+
+        $this->assertSame(Status::FORBIDDEN, $response->status);
+    }
+
+    #[Test]
+    public function invalid_signature_returns_forbidden(): void
+    {
+        $uri = $this->generator->createSignedUri(
+            action: [SignedUrlController::class, 'signedAction'],
+            token: 'abc123',
+        );
+
+        // Tamper with the signature
+        $tamperedUri = str_replace('signature=', 'signature=tampered', $uri);
+
+        $response = $this->http->get($tamperedUri);
+
+        $this->assertSame(Status::FORBIDDEN, $response->status);
+    }
+
+    #[Test]
+    public function tampered_parameter_returns_forbidden(): void
+    {
+        $uri = $this->generator->createSignedUri(
+            action: [SignedUrlController::class, 'signedAction'],
+            token: 'abc123',
+        );
+
+        // Tamper with the token parameter
+        $tamperedUri = str_replace('abc123', 'tampered', $uri);
+
+        $response = $this->http->get($tamperedUri);
+
+        $this->assertSame(Status::FORBIDDEN, $response->status);
+    }
+
+    #[Test]
+    public function expired_signature_returns_forbidden(): void
+    {
+        $clock = $this->clock();
+
+        $uri = $this->generator->createTemporarySignedUri(
+            action: [SignedUrlController::class, 'signedAction'],
+            duration: Duration::minutes(10),
+            token: 'abc123',
+        );
+
+        // Advance time past expiration
+        $clock->plus(Duration::minutes(15));
+
+        $response = $this->http->get($uri);
+
+        $this->assertSame(Status::FORBIDDEN, $response->status);
+    }
+
+    #[Test]
+    public function temporary_signature_valid_before_expiration(): void
+    {
+        $clock = $this->clock();
+
+        $uri = $this->generator->createTemporarySignedUri(
+            action: [SignedUrlController::class, 'signedAction'],
+            duration: Duration::minutes(10),
+            token: 'abc123',
+        );
+
+        // Advance time but stay within expiration
+        $clock->plus(Duration::minutes(5));
+
+        $response = $this->http->get($uri);
+
+        $this->assertSame(Status::OK, $response->status);
+    }
+
+    #[Test]
+    public function unsigned_route_works_without_signature(): void
+    {
+        // Routes without #[ValidSignature] should work normally
+        $response = $this->http->get('/unsigned-action/abc123');
+
+        $this->assertSame(Status::OK, $response->status);
+    }
+
+    #[Test]
+    public function tampered_expiration_returns_forbidden(): void
+    {
+        $clock = $this->clock();
+
+        $uri = $this->generator->createTemporarySignedUri(
+            action: [SignedUrlController::class, 'signedAction'],
+            duration: Duration::minutes(10),
+            token: 'abc123',
+        );
+
+        // Get the current timestamp and extend it in the URL
+        $timestamp = $clock->now()->plusMinutes(10)->getTimestamp()->getSeconds();
+        $tamperedUri = str_replace(
+            'expires_at=' . $timestamp,
+            'expires_at=' . ($timestamp + 3600),
+            $uri
+        );
+
+        $response = $this->http->get($tamperedUri);
+
+        $this->assertSame(Status::FORBIDDEN, $response->status);
+    }
+}