diff --git a/CHANGELOG.md b/CHANGELOG.md
index f39b091e..84d17f4d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,8 @@
+### v4.25.2 (2026-08-18)
+* * *
+### Bug Fixes: 
+- HTTP methods are now uppercased before a request is constructed, so the SDK no longer emits deprecation notices from `guzzlehttp/psr7` 2.11+ (`Passing a non-uppercase HTTP method is deprecated`) or `guzzlehttp/guzzle` 7.11+. Both libraries preserve method casing in their next major versions, where a lowercase method would have been sent on the wire as-is.
+
 ### v4.25.1 (2026-08-11)
 * * *
 ### Bug Fixes: 
diff --git a/VERSION b/VERSION
index 72e19f2f..52665044 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-4.25.1
+4.25.2
diff --git a/src/HttpClient/GuzzleFactory.php b/src/HttpClient/GuzzleFactory.php
index 01895e4c..0febdc6d 100644
--- a/src/HttpClient/GuzzleFactory.php
+++ b/src/HttpClient/GuzzleFactory.php
@@ -42,7 +42,7 @@ public function create(): \Psr\Http\Client\ClientInterface
 
     public function createRequest(ChargebeePayload $chargebeePayload): \Psr\Http\Message\RequestInterface
     {
-        $httpMethod = $chargebeePayload->getHttpMethod();
+        $httpMethod = strtolower($chargebeePayload->getHttpMethod());
         $params = $chargebeePayload->getSerializedParameters();
         $headers = $chargebeePayload->getHeaders();
 
@@ -54,7 +54,7 @@ public function createRequest(ChargebeePayload $chargebeePayload): \Psr\Http\Mes
         $uri = new Uri($url);
         $body = null;
 
-        if ($chargebeePayload->getHttpMethod() == "get") {
+        if ($httpMethod == "get") {
             if (!empty($params)) {
                 $uri = $uri->withQuery($params);
             }
@@ -63,7 +63,7 @@ public function createRequest(ChargebeePayload $chargebeePayload): \Psr\Http\Mes
         if ($httpMethod == "post") {
             $body = $params;
         }
-        return new \GuzzleHttp\Psr7\Request($httpMethod, $uri, $headers, $body);
+        return new \GuzzleHttp\Psr7\Request(strtoupper($httpMethod), $uri, $headers, $body);
     }
 
     public static function utf8($value)
diff --git a/src/HttpClient/PsrClientAdapter.php b/src/HttpClient/PsrClientAdapter.php
index f4fef3b2..dfd11ffc 100644
--- a/src/HttpClient/PsrClientAdapter.php
+++ b/src/HttpClient/PsrClientAdapter.php
@@ -24,7 +24,7 @@ public function create(): ClientInterface
 
     public function createRequest(ChargebeePayload $payload): RequestInterface
     {
-        $httpMethod = $payload->getHttpMethod();
+        $httpMethod = strtolower($payload->getHttpMethod());
         $params     = $payload->getSerializedParameters();
         $headers    = $payload->getHeaders();
 
diff --git a/src/Version.php b/src/Version.php
index aa6a6013..3f65901a 100644
--- a/src/Version.php
+++ b/src/Version.php
@@ -4,7 +4,7 @@
 
 final class Version
 {
-	const VERSION = '4.25.1';
+	const VERSION = '4.25.2';
 }
 
 ?>
\ No newline at end of file
diff --git a/tests/Network/GuzzleFactoryTest.php b/tests/Network/GuzzleFactoryTest.php
new file mode 100644
index 00000000..b80ead6a
--- /dev/null
+++ b/tests/Network/GuzzleFactoryTest.php
@@ -0,0 +1,57 @@
+<?php
+
+namespace Tests\Network;
+
+use Chargebee\Environment;
+use Chargebee\HttpClient\GuzzleFactory;
+use Chargebee\ValueObjects\Transporters\ChargebeePayload;
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\Attributes\TestDox;
+use PHPUnit\Framework\TestCase;
+
+#[CoversClass(GuzzleFactory::class)]
+final class GuzzleFactoryTest extends TestCase
+{
+    private function makePayload(string $method, ?string $params = null): ChargebeePayload
+    {
+        $env = new Environment('test-site', 'test-api-key');
+        return new ChargebeePayload(
+            'https://example.com/api/v2/customers',
+            $method,
+            $params,
+            ['Authorization' => 'Basic dGVzdA=='],
+            $env
+        );
+    }
+
+    #[TestDox('createRequest() builds a request with an uppercase HTTP method')]
+    #[DataProvider('httpMethodProvider')]
+    public function testCreateRequestUsesUppercaseHttpMethod(string $method, string $expected): void
+    {
+        $factory = new GuzzleFactory(10, 30);
+
+        $request = $factory->createRequest($this->makePayload($method, 'limit=10'));
+
+        $this->assertSame($expected, $request->getMethod());
+    }
+
+    public static function httpMethodProvider(): array
+    {
+        return [
+            'lowercase get' => ['get', 'GET'],
+            'lowercase post' => ['post', 'POST'],
+            'uppercase get' => ['GET', 'GET'],
+            'uppercase post' => ['POST', 'POST'],
+        ];
+    }
+
+    #[TestDox('createRequest() rejects unsupported HTTP methods')]
+    public function testCreateRequestRejectsUnsupportedMethod(): void
+    {
+        $factory = new GuzzleFactory(10, 30);
+
+        $this->expectException(\Exception::class);
+        $factory->createRequest($this->makePayload('delete'));
+    }
+}
diff --git a/tests/Network/MockGuzzleFactory.php b/tests/Network/MockGuzzleFactory.php
index a0e503e9..f8ff710c 100644
--- a/tests/Network/MockGuzzleFactory.php
+++ b/tests/Network/MockGuzzleFactory.php
@@ -132,7 +132,7 @@ public function sendRequest(RequestInterface $request): ResponseInterface
 
     public function createRequest(ChargebeePayload $chargebeePayload): RequestInterface
     {
-        $httpMethod = $chargebeePayload->getHttpMethod();
+        $httpMethod = strtolower($chargebeePayload->getHttpMethod());
         $params = $chargebeePayload->getSerializedParameters();
         $headers = $chargebeePayload->getHeaders();
 
@@ -152,7 +152,7 @@ public function createRequest(ChargebeePayload $chargebeePayload): RequestInterf
             $body = $params;
         }
 
-        return new Request($httpMethod, $uri, $headers, $body);
+        return new Request(strtoupper($httpMethod), $uri, $headers, $body);
     }
 
     /**