diff --git a/src/Subscriber/CongratulateFirstTimeMergedContributorSubscriber.php b/src/Subscriber/CongratulateFirstTimeMergedContributorSubscriber.php
new file mode 100644
index 00000000..f1909d5c
--- /dev/null
+++ b/src/Subscriber/CongratulateFirstTimeMergedContributorSubscriber.php
@@ -0,0 +1,63 @@
+<?php
+
+namespace App\Subscriber;
+
+use App\Api\Issue\IssueApi;
+use App\Event\GitHubEvent;
+use App\GitHubEvents;
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+
+/**
+ * @author Ayyoub AFW-ALLAH <ayyoub.afwallah@gmail.com>
+ */
+class CongratulateFirstTimeMergedContributorSubscriber implements EventSubscriberInterface
+{
+    public function __construct(
+        private readonly IssueApi $issueApi,
+    ) {
+    }
+
+    public function onPullRequest(GitHubEvent $event): void
+    {
+        $data = $event->getData();
+        if ('closed' !== $data['action'] || !($data['merged'] ?? false)) {
+            return;
+        }
+
+        $association = $data['pull_request']['author_association'] ?? '';
+        if (!in_array($association, ['NONE', 'FIRST_TIMER', 'FIRST_TIME_CONTRIBUTOR'])) {
+            return;
+        }
+
+        $repository = $event->getRepository();
+        $pullRequestNumber = $data['pull_request']['number'];
+        $goodFirstIssueUrl = sprintf(
+            'https://github.com/%s/issues?q=is%%3Aissue%%20state%%3Aopen%%20label%%3A%%22Good%%20first%%20issue%%22',
+            $repository->getFullName()
+        );
+
+        $this->issueApi->commentOnIssue($repository, $pullRequestNumber, <<<TXT
+Your first PR just merged. You're officially a Symfony contributor — welcome to the club! 🎉
+
+Whenever you're ready for more, [good first issue]($goodFirstIssueUrl) is a great place to start. Got ideas, found a bug, or just want to help? We're always here.
+
+Carsonbot
+TXT
+        );
+
+        $event->setResponseData([
+            'pull_request' => $pullRequestNumber,
+            'first_time_merged_contributor' => true,
+        ]);
+    }
+
+    /**
+     * @return array<string, string>
+     */
+    public static function getSubscribedEvents(): array
+    {
+        return [
+            GitHubEvents::PULL_REQUEST => 'onPullRequest',
+        ];
+    }
+}
diff --git a/tests/Subscriber/CongratulateFirstTimeMergedContributorSubscriberTest.php b/tests/Subscriber/CongratulateFirstTimeMergedContributorSubscriberTest.php
new file mode 100644
index 00000000..b0132441
--- /dev/null
+++ b/tests/Subscriber/CongratulateFirstTimeMergedContributorSubscriberTest.php
@@ -0,0 +1,95 @@
+<?php
+
+namespace App\Tests\Subscriber;
+
+use App\Api\Issue\IssueApi;
+use App\Event\GitHubEvent;
+use App\GitHubEvents;
+use App\Model\Repository;
+use App\Subscriber\CongratulateFirstTimeMergedContributorSubscriber;
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\EventDispatcher\EventDispatcher;
+
+class CongratulateFirstTimeMergedContributorSubscriberTest extends TestCase
+{
+    private IssueApi $issueApi;
+    private Repository $repository;
+    private EventDispatcher $dispatcher;
+
+    protected function setUp(): void
+    {
+        $this->issueApi = $this->createMock(IssueApi::class);
+        $this->repository = new Repository('symfony', 'symfony', null);
+
+        $this->dispatcher = new EventDispatcher();
+        $this->dispatcher->addSubscriber(new CongratulateFirstTimeMergedContributorSubscriber($this->issueApi));
+    }
+
+    public function testPostsCommentOnFirstTimeMergedContributor()
+    {
+        $this->issueApi->expects($this->once())
+            ->method('commentOnIssue')
+            ->with(
+                $this->repository,
+                1234,
+                $this->stringContains("You're officially a Symfony contributor — welcome to the club!")
+            );
+
+        $this->dispatcher->dispatch(new GitHubEvent([
+            'action' => 'closed',
+            'merged' => true,
+            'pull_request' => [
+                'number' => 1234,
+                'author_association' => 'FIRST_TIME_CONTRIBUTOR',
+            ],
+        ], $this->repository), GitHubEvents::PULL_REQUEST);
+    }
+
+    public function testSkipsNonMergedClosedPR()
+    {
+        $this->issueApi->expects($this->never())->method('commentOnIssue');
+
+        $this->dispatcher->dispatch(new GitHubEvent([
+            'action' => 'closed',
+            'merged' => false,
+            'pull_request' => [
+                'number' => 1234,
+                'author_association' => 'FIRST_TIME_CONTRIBUTOR',
+            ],
+        ], $this->repository), GitHubEvents::PULL_REQUEST);
+    }
+
+    public function testSkipsExistingContributor()
+    {
+        $this->issueApi->expects($this->never())->method('commentOnIssue');
+
+        $this->dispatcher->dispatch(new GitHubEvent([
+            'action' => 'closed',
+            'merged' => true,
+            'pull_request' => [
+                'number' => 1234,
+                'author_association' => 'CONTRIBUTOR',
+            ],
+        ], $this->repository), GitHubEvents::PULL_REQUEST);
+    }
+
+    public function testGoodFirstIssueLinkPointsToCorrectRepo()
+    {
+        $this->issueApi->expects($this->once())
+            ->method('commentOnIssue')
+            ->with(
+                $this->repository,
+                1234,
+                $this->stringContains('https://github.com/symfony/symfony/issues?q=is%3Aissue%20state%3Aopen%20label%3A%22Good%20first%20issue%22')
+            );
+
+        $this->dispatcher->dispatch(new GitHubEvent([
+            'action' => 'closed',
+            'merged' => true,
+            'pull_request' => [
+                'number' => 1234,
+                'author_association' => 'FIRST_TIMER',
+            ],
+        ], $this->repository), GitHubEvents::PULL_REQUEST);
+    }
+}