diff --git a/src/Providers/Http/DTO/BearerTokenRequestAuthentication.php b/src/Providers/Http/DTO/BearerTokenRequestAuthentication.php
new file mode 100644
index 00000000..153904b8
--- /dev/null
+++ b/src/Providers/Http/DTO/BearerTokenRequestAuthentication.php
@@ -0,0 +1,109 @@
+<?php
+
+declare(strict_types=1);
+
+namespace WordPress\AiClient\Providers\Http\DTO;
+
+use WordPress\AiClient\Common\AbstractDataTransferObject;
+use WordPress\AiClient\Providers\Http\Contracts\RequestAuthenticationInterface;
+
+/**
+ * Class for HTTP request authentication using a bearer token.
+ *
+ * @since n.e.x.t
+ *
+ * @phpstan-type BearerTokenRequestAuthenticationArrayShape array{
+ *     bearerToken: string
+ * }
+ *
+ * @extends AbstractDataTransferObject<BearerTokenRequestAuthenticationArrayShape>
+ */
+class BearerTokenRequestAuthentication extends AbstractDataTransferObject implements RequestAuthenticationInterface
+{
+    public const KEY_BEARER_TOKEN = 'bearerToken';
+
+    /**
+     * @var string The bearer token used for authentication.
+     */
+    protected string $bearerToken;
+
+    /**
+     * Constructor.
+     *
+     * @since n.e.x.t
+     *
+     * @param string $bearerToken The bearer token used for authentication.
+     */
+    public function __construct(string $bearerToken)
+    {
+        $this->bearerToken = $bearerToken;
+    }
+
+    /**
+     * {@inheritDoc}
+     *
+     * @since n.e.x.t
+     */
+    public function authenticateRequest(Request $request): Request
+    {
+        return $request->withHeader('Authorization', 'Bearer ' . $this->bearerToken);
+    }
+
+    /**
+     * Gets the bearer token.
+     *
+     * @since n.e.x.t
+     *
+     * @return string The bearer token.
+     */
+    public function getBearerToken(): string
+    {
+        return $this->bearerToken;
+    }
+
+    /**
+     * {@inheritDoc}
+     *
+     * @since n.e.x.t
+     *
+     * @return BearerTokenRequestAuthenticationArrayShape
+     */
+    public function toArray(): array
+    {
+        return [
+            self::KEY_BEARER_TOKEN => $this->bearerToken,
+        ];
+    }
+
+    /**
+     * {@inheritDoc}
+     *
+     * @since n.e.x.t
+     */
+    public static function fromArray(array $array): self
+    {
+        static::validateFromArrayData($array, [self::KEY_BEARER_TOKEN]);
+
+        return new self($array[self::KEY_BEARER_TOKEN]);
+    }
+
+    /**
+     * {@inheritDoc}
+     *
+     * @since n.e.x.t
+     */
+    public static function getJsonSchema(): array
+    {
+        return [
+            'type' => 'object',
+            'properties' => [
+                self::KEY_BEARER_TOKEN => [
+                    'type' => 'string',
+                    'title' => 'Bearer Token',
+                    'description' => 'The bearer token used for authentication.',
+                ],
+            ],
+            'required' => [self::KEY_BEARER_TOKEN],
+        ];
+    }
+}
diff --git a/src/Providers/Http/Enums/RequestAuthenticationMethod.php b/src/Providers/Http/Enums/RequestAuthenticationMethod.php
index 1fb92dbc..fbd3141e 100644
--- a/src/Providers/Http/Enums/RequestAuthenticationMethod.php
+++ b/src/Providers/Http/Enums/RequestAuthenticationMethod.php
@@ -8,6 +8,7 @@
 use WordPress\AiClient\Common\Contracts\WithArrayTransformationInterface;
 use WordPress\AiClient\Providers\Http\Contracts\RequestAuthenticationInterface;
 use WordPress\AiClient\Providers\Http\DTO\ApiKeyRequestAuthentication;
+use WordPress\AiClient\Providers\Http\DTO\BearerTokenRequestAuthentication;
 
 /**
  * Enum for request authentication methods.
@@ -15,7 +16,9 @@
  * @since 0.4.0
  *
  * @method static self apiKey() Creates an instance for API_KEY method.
+ * @method static self bearerToken() Creates an instance for BEARER_TOKEN method.
  * @method bool isApiKey() Checks if the method is API_KEY.
+ * @method bool isBearerToken() Checks if the method is BEARER_TOKEN.
  */
 class RequestAuthenticationMethod extends AbstractEnum
 {
@@ -24,6 +27,13 @@ class RequestAuthenticationMethod extends AbstractEnum
      */
     public const API_KEY = 'api_key';
 
+    /**
+     * Bearer token authentication.
+     *
+     * @since n.e.x.t
+     */
+    public const BEARER_TOKEN = 'bearer_token';
+
     /**
      * Gets the implementation class for the authentication method.
      *
@@ -35,8 +45,10 @@ class RequestAuthenticationMethod extends AbstractEnum
      */
     public function getImplementationClass(): string
     {
-        // At the moment, this is the only supported method.
-        // Once more methods are available, add conditionals here for each method.
+        if ($this->isBearerToken()) {
+            return BearerTokenRequestAuthentication::class;
+        }
+
         return ApiKeyRequestAuthentication::class;
     }
 }
diff --git a/tests/mocks/MockCustomAuthModel.php b/tests/mocks/MockCustomAuthModel.php
new file mode 100644
index 00000000..37698b4b
--- /dev/null
+++ b/tests/mocks/MockCustomAuthModel.php
@@ -0,0 +1,21 @@
+<?php
+
+declare(strict_types=1);
+
+namespace WordPress\AiClient\Tests\mocks;
+
+use WordPress\AiClient\Providers\DTO\ProviderMetadata;
+
+/**
+ * Mock model for the custom authentication provider.
+ */
+class MockCustomAuthModel extends MockModel
+{
+    /**
+     * {@inheritDoc}
+     */
+    public function providerMetadata(): ProviderMetadata
+    {
+        return MockCustomAuthProvider::metadata();
+    }
+}
diff --git a/tests/mocks/MockCustomAuthProvider.php b/tests/mocks/MockCustomAuthProvider.php
new file mode 100644
index 00000000..2034435a
--- /dev/null
+++ b/tests/mocks/MockCustomAuthProvider.php
@@ -0,0 +1,50 @@
+<?php
+
+declare(strict_types=1);
+
+namespace WordPress\AiClient\Tests\mocks;
+
+use WordPress\AiClient\Providers\DTO\ProviderMetadata;
+use WordPress\AiClient\Providers\Enums\ProviderTypeEnum;
+use WordPress\AiClient\Providers\Http\Enums\RequestAuthenticationMethod;
+use WordPress\AiClient\Providers\Models\Contracts\ModelInterface;
+use WordPress\AiClient\Providers\Models\DTO\ModelConfig;
+
+/**
+ * Mock provider with bearer token authentication for testing purposes.
+ */
+class MockCustomAuthProvider extends MockProvider
+{
+    /**
+     * {@inheritDoc}
+     */
+    public static function metadata(): ProviderMetadata
+    {
+        return new ProviderMetadata(
+            'mock-custom-auth',
+            'Mock Custom Auth Provider',
+            ProviderTypeEnum::cloud(),
+            null,
+            RequestAuthenticationMethod::bearerToken()
+        );
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public static function model(string $modelId, ?ModelConfig $modelConfig = null): ModelInterface
+    {
+        $modelMetadata = static::modelMetadataDirectory()->getModelMetadata($modelId);
+        $config = $modelConfig ?? new ModelConfig();
+
+        return new MockCustomAuthModel($modelMetadata, $config);
+    }
+
+    /**
+     * Resets static state for testing.
+     */
+    public static function reset(): void
+    {
+        parent::reset();
+    }
+}
diff --git a/tests/mocks/MockCustomRequestAuthentication.php b/tests/mocks/MockCustomRequestAuthentication.php
new file mode 100644
index 00000000..c851ee2f
--- /dev/null
+++ b/tests/mocks/MockCustomRequestAuthentication.php
@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace WordPress\AiClient\Tests\mocks;
+
+use WordPress\AiClient\Providers\Http\DTO\BearerTokenRequestAuthentication;
+use WordPress\AiClient\Providers\Http\DTO\Request;
+
+/**
+ * Mock custom request authentication for testing purposes.
+ */
+class MockCustomRequestAuthentication extends BearerTokenRequestAuthentication
+{
+    /**
+     * {@inheritDoc}
+     */
+    public function authenticateRequest(Request $request): Request
+    {
+        return parent::authenticateRequest($request)->withHeader('X-Mock-Auth', 'custom');
+    }
+}
diff --git a/tests/unit/Providers/ProviderRegistryTest.php b/tests/unit/Providers/ProviderRegistryTest.php
index ff8197e6..f60d6a51 100644
--- a/tests/unit/Providers/ProviderRegistryTest.php
+++ b/tests/unit/Providers/ProviderRegistryTest.php
@@ -8,12 +8,15 @@
 use PHPUnit\Framework\TestCase;
 use WordPress\AiClient\Providers\Http\Contracts\RequestAuthenticationInterface;
 use WordPress\AiClient\Providers\Http\DTO\ApiKeyRequestAuthentication;
+use WordPress\AiClient\Providers\Http\DTO\BearerTokenRequestAuthentication;
 use WordPress\AiClient\Providers\Http\DTO\Request;
 use WordPress\AiClient\Providers\Models\DTO\ModelConfig;
 use WordPress\AiClient\Providers\Models\DTO\ModelMetadata;
 use WordPress\AiClient\Providers\Models\DTO\ModelRequirements;
 use WordPress\AiClient\Providers\Models\Enums\CapabilityEnum;
 use WordPress\AiClient\Providers\ProviderRegistry;
+use WordPress\AiClient\Tests\mocks\MockCustomAuthProvider;
+use WordPress\AiClient\Tests\mocks\MockCustomRequestAuthentication;
 use WordPress\AiClient\Tests\mocks\MockHttpTransporter;
 use WordPress\AiClient\Tests\mocks\MockModel;
 use WordPress\AiClient\Tests\mocks\MockModelMetadataDirectory;
@@ -32,12 +35,14 @@ protected function setUp(): void
     {
         parent::setUp();
         $this->registry = new ProviderRegistry();
+        MockCustomAuthProvider::reset();
         MockProvider::reset(); // Reset static state of mock provider before each test.
     }
 
     protected function tearDown(): void
     {
         MockProvider::reset(); // Reset static state of mock provider after each test.
+        MockCustomAuthProvider::reset();
         parent::tearDown();
     }
 
@@ -376,6 +381,46 @@ public function testGetProviderRequestAuthenticationReturnsDefault(): void
         $this->assertNull($retrievedAuth);
     }
 
+    /**
+     * Tests that explicit bearer token authentication is bound to models.
+     *
+     * @return void
+     */
+    public function testSetProviderRequestAuthenticationBindsBearerTokenAuthenticationToModels(): void
+    {
+        $this->registry->registerProvider(MockCustomAuthProvider::class);
+
+        $requestAuthentication = new MockCustomRequestAuthentication('test-token');
+        $this->registry->setProviderRequestAuthentication('mock-custom-auth', $requestAuthentication);
+
+        $model = $this->registry->getProviderModel('mock-custom-auth', 'mock-text-model');
+
+        $this->assertSame(
+            $requestAuthentication,
+            $this->registry->getProviderRequestAuthentication('mock-custom-auth')
+        );
+        $this->assertSame($requestAuthentication, $model->getRequestAuthentication());
+    }
+
+    /**
+     * Tests default bearer token authentication creation from environment data.
+     *
+     * @return void
+     */
+    public function testCreateDefaultProviderRequestAuthenticationWithBearerTokenEnvVar(): void
+    {
+        putenv('MOCK_CUSTOM_AUTH_BEARER_TOKEN=test_bearer_token');
+
+        $this->registry->registerProvider(MockCustomAuthProvider::class);
+
+        $auth = $this->registry->getProviderRequestAuthentication('mock-custom-auth');
+
+        $this->assertInstanceOf(BearerTokenRequestAuthentication::class, $auth);
+        $this->assertSame('test_bearer_token', $auth->getBearerToken());
+
+        putenv('MOCK_CUSTOM_AUTH_BEARER_TOKEN');
+    }
+
     /**
      * Tests the internal getEnvVarName method using reflection.
      *
@@ -388,7 +433,9 @@ public function testGetProviderRequestAuthenticationReturnsDefault(): void
     public function testGetEnvVarName(string $providerId, string $field, string $expected): void
     {
         $method = new \ReflectionMethod(ProviderRegistry::class, 'getEnvVarName');
-        $method->setAccessible(true);
+        if (PHP_VERSION_ID < 80100) {
+            $method->setAccessible(true);
+        }
 
         $result = $method->invoke($this->registry, $providerId, $field); // Invoke on instance
 
@@ -424,7 +471,9 @@ public function testCreateDefaultProviderRequestAuthenticationWithEnvVar(): void
         $this->registry->registerProvider(MockProvider::class);
 
         $method = new \ReflectionMethod(ProviderRegistry::class, 'createDefaultProviderRequestAuthentication');
-        $method->setAccessible(true);
+        if (PHP_VERSION_ID < 80100) {
+            $method->setAccessible(true);
+        }
 
         $auth = $method->invoke($this->registry, MockProvider::class);
 
@@ -448,7 +497,9 @@ public function testCreateDefaultProviderRequestAuthenticationWithoutEnvVar(): v
         $this->registry->registerProvider(MockProvider::class);
 
         $method = new \ReflectionMethod(ProviderRegistry::class, 'createDefaultProviderRequestAuthentication');
-        $method->setAccessible(true);
+        if (PHP_VERSION_ID < 80100) {
+            $method->setAccessible(true);
+        }
 
         $auth = $method->invoke($this->registry, MockProvider::class);