diff --git a/system/CodeIgniter.php b/system/CodeIgniter.php
index 3eecebfbed31..3e12e4e121b1 100644
--- a/system/CodeIgniter.php
+++ b/system/CodeIgniter.php
@@ -21,6 +21,7 @@
 use CodeIgniter\HTTP\DownloadResponse;
 use CodeIgniter\HTTP\Exceptions\RedirectException;
 use CodeIgniter\HTTP\IncomingRequest;
+use CodeIgniter\HTTP\Method;
 use CodeIgniter\HTTP\RedirectResponse;
 use CodeIgniter\HTTP\Request;
 use CodeIgniter\HTTP\ResponsableInterface;
@@ -1027,7 +1028,7 @@ public function storePreviousURL($uri)
     public function spoofRequestMethod()
     {
         // Only works with POSTED forms
-        if ($this->request->getMethod() !== 'POST') {
+        if ($this->request->getMethod() !== Method::POST) {
             return;
         }
 
@@ -1038,7 +1039,7 @@ public function spoofRequestMethod()
         }
 
         // Only allows PUT, PATCH, DELETE
-        if (in_array($method, ['PUT', 'PATCH', 'DELETE'], true)) {
+        if (in_array($method, [Method::PUT, Method::PATCH, Method::DELETE], true)) {
             $this->request = $this->request->setMethod($method);
         }
     }
diff --git a/system/HTTP/CURLRequest.php b/system/HTTP/CURLRequest.php
index 48605b1e8274..9f5cd61ab275 100644
--- a/system/HTTP/CURLRequest.php
+++ b/system/HTTP/CURLRequest.php
@@ -112,7 +112,7 @@ public function __construct(App $config, URI $uri, ?ResponseInterface $response
             throw HTTPException::forMissingCurl(); // @codeCoverageIgnore
         }
 
-        parent::__construct('GET', $uri);
+        parent::__construct(Method::GET, $uri);
 
         $this->responseOrig   = $response ?? new Response(config(App::class));
         $this->baseURI        = $uri->useRawQueryString();
@@ -177,7 +177,7 @@ protected function resetOptions()
      */
     public function get(string $url, array $options = []): ResponseInterface
     {
-        return $this->request('GET', $url, $options);
+        return $this->request(Method::GET, $url, $options);
     }
 
     /**
@@ -217,7 +217,7 @@ public function patch(string $url, array $options = []): ResponseInterface
      */
     public function post(string $url, array $options = []): ResponseInterface
     {
-        return $this->request('POST', $url, $options);
+        return $this->request(Method::POST, $url, $options);
     }
 
     /**
@@ -225,7 +225,7 @@ public function post(string $url, array $options = []): ResponseInterface
      */
     public function put(string $url, array $options = []): ResponseInterface
     {
-        return $this->request('PUT', $url, $options);
+        return $this->request(Method::PUT, $url, $options);
     }
 
     /**
@@ -445,7 +445,7 @@ protected function applyMethod(string $method, array $curlOptions): array
             return $this->applyBody($curlOptions);
         }
 
-        if ($method === 'PUT' || $method === 'POST') {
+        if ($method === Method::PUT || $method === Method::POST) {
             // See http://tools.ietf.org/html/rfc7230#section-3.3.2
             if ($this->header('content-length') === null && ! isset($this->config['multipart'])) {
                 $this->setHeader('Content-Length', '0');
diff --git a/system/HTTP/IncomingRequest.php b/system/HTTP/IncomingRequest.php
index 3acd90b2a00b..8af3e86991ac 100755
--- a/system/HTTP/IncomingRequest.php
+++ b/system/HTTP/IncomingRequest.php
@@ -404,7 +404,7 @@ public function is(string $type): bool
     {
         $valueUpper = strtoupper($type);
 
-        $httpMethods = ['GET', 'POST', 'PUT', 'DELETE', 'HEAD', 'PATCH', 'OPTIONS'];
+        $httpMethods = Method::all();
 
         if (in_array($valueUpper, $httpMethods, true)) {
             return $this->getMethod() === $valueUpper;
diff --git a/system/HTTP/Request.php b/system/HTTP/Request.php
index 462cb5731952..1466175c7b8f 100644
--- a/system/HTTP/Request.php
+++ b/system/HTTP/Request.php
@@ -41,7 +41,7 @@ class Request extends OutgoingRequest implements RequestInterface
     public function __construct($config = null) // @phpstan-ignore-line
     {
         if (empty($this->method)) {
-            $this->method = $this->getServer('REQUEST_METHOD') ?? 'GET';
+            $this->method = $this->getServer('REQUEST_METHOD') ?? Method::GET;
         }
 
         if (empty($this->uri)) {
diff --git a/system/HTTP/ResponseTrait.php b/system/HTTP/ResponseTrait.php
index 9c4344e81c40..8d8cad504866 100644
--- a/system/HTTP/ResponseTrait.php
+++ b/system/HTTP/ResponseTrait.php
@@ -442,9 +442,9 @@ public function redirect(string $uri, string $method = 'auto', ?int $code = null
                 isset($_SERVER['SERVER_PROTOCOL'], $_SERVER['REQUEST_METHOD'])
                 && $this->getProtocolVersion() >= 1.1
             ) {
-                if ($_SERVER['REQUEST_METHOD'] === 'GET') {
+                if ($_SERVER['REQUEST_METHOD'] === Method::GET) {
                     $code = 302;
-                } elseif (in_array($_SERVER['REQUEST_METHOD'], ['POST', 'PUT', 'DELETE'], true)) {
+                } elseif (in_array($_SERVER['REQUEST_METHOD'], [Method::POST, Method::PUT, Method::DELETE], true)) {
                     // reference: https://en.wikipedia.org/wiki/Post/Redirect/Get
                     $code = 303;
                 } else {
diff --git a/system/Security/Security.php b/system/Security/Security.php
index 3868b19f8d84..9c28b82335b0 100644
--- a/system/Security/Security.php
+++ b/system/Security/Security.php
@@ -13,6 +13,7 @@
 
 use CodeIgniter\Cookie\Cookie;
 use CodeIgniter\HTTP\IncomingRequest;
+use CodeIgniter\HTTP\Method;
 use CodeIgniter\HTTP\Request;
 use CodeIgniter\HTTP\RequestInterface;
 use CodeIgniter\I18n\Time;
@@ -281,7 +282,7 @@ public function verify(RequestInterface $request)
     {
         // Protects POST, PUT, DELETE, PATCH
         $method           = $request->getMethod();
-        $methodsToProtect = ['POST', 'PUT', 'DELETE', 'PATCH'];
+        $methodsToProtect = [Method::POST, Method::PUT, Method::DELETE, Method::PATCH];
         if (! in_array($method, $methodsToProtect, true)) {
             return $this;
         }
diff --git a/system/Validation/Validation.php b/system/Validation/Validation.php
index ae4f030907b4..6313ea62c4fa 100644
--- a/system/Validation/Validation.php
+++ b/system/Validation/Validation.php
@@ -13,6 +13,7 @@
 
 use Closure;
 use CodeIgniter\HTTP\IncomingRequest;
+use CodeIgniter\HTTP\Method;
 use CodeIgniter\HTTP\RequestInterface;
 use CodeIgniter\Validation\Exceptions\ValidationException;
 use CodeIgniter\View\RendererInterface;
@@ -501,7 +502,7 @@ public function withRequest(RequestInterface $request): ValidationInterface
             return $this;
         }
 
-        if (in_array($request->getMethod(), ['PUT', 'PATCH', 'DELETE'], true)
+        if (in_array($request->getMethod(), [Method::PUT, Method::PATCH, Method::DELETE], true)
             && strpos($request->getHeaderLine('Content-Type'), 'multipart/form-data') === false
         ) {
             $this->data = $request->getRawInput();