diff --git a/config/services.yaml b/config/services.yaml
index e06624d..6590355 100644
--- a/config/services.yaml
+++ b/config/services.yaml
@@ -125,6 +125,10 @@ services:
         tags:
             - { name: doctrine.orm.entity_listener, entity: 'App\Module\Directory\Domain\Entity\CommercialReport', event: prePersist }
 
+    App\Module\ProjectManagement\Infrastructure\EventListener\ProjectDefaultWorkflowListener:
+        tags:
+            - { name: doctrine.orm.entity_listener, entity: 'App\Module\ProjectManagement\Domain\Entity\Project', event: prePersist }
+
     App\Module\Directory\Infrastructure\ApiPlatform\State\ReportDocumentProcessor:
         arguments:
             $uploadDir: '%task_document_upload_dir%'
diff --git a/frontend/modules/project-management/components/ProjectDrawer.vue b/frontend/modules/project-management/components/ProjectDrawer.vue
index eff00db..19a4641 100644
--- a/frontend/modules/project-management/components/ProjectDrawer.vue
+++ b/frontend/modules/project-management/components/ProjectDrawer.vue
@@ -32,6 +32,13 @@
                 empty-option-label="Aucun client"
                 group-class="w-full"
             />
+            <MalioSelect
+                v-if="!isEditing"
+                v-model="form.workflowId"
+                :options="workflowOptions"
+                label="Workflow"
+                group-class="w-full"
+            />
             <div class="mt-4">
                 <ColorPicker v-model="form.color" />
             </div>
@@ -124,10 +131,12 @@
 
 <script setup lang="ts">
 import type { Project, ProjectWrite } from '~/modules/project-management/services/dto/project'
+import type { Workflow } from '~/modules/project-management/services/dto/workflow'
 import type { Client } from '~/modules/directory/services/dto/client'
 import type { GiteaRepository } from '~/modules/integration/services/dto/gitea'
 import type { BookStackShelf } from '~/modules/integration/services/dto/bookstack'
 import { useProjectService } from '~/modules/project-management/services/projects'
+import { useWorkflowService } from '~/modules/project-management/services/workflows'
 import { useGiteaService } from '~/modules/integration/services/gitea'
 import { useBookStackService } from '~/modules/integration/services/bookstack'
 
@@ -174,12 +183,24 @@ const bookstackShelfOptions = computed(() =>
     bookstackShelves.value.map(s => ({ label: s.name, value: s.id }))
 )
 
+const { getAll: getAllWorkflows } = useWorkflowService()
+const workflows = ref<Workflow[]>([])
+
+const workflowOptions = computed(() =>
+    workflows.value.map(w => ({ label: w.name, value: w.id }))
+)
+
+function defaultWorkflowId(): number | null {
+    return (workflows.value.find(w => w.isDefault) ?? workflows.value[0])?.id ?? null
+}
+
 const form = reactive({
     code: '',
     name: '',
     description: '',
     color: '#222783',
     clientId: null as number | null,
+    workflowId: null as number | null,
     giteaRepoFullName: null as string | null,
     bookstackShelfId: null as number | null,
 })
@@ -222,6 +243,7 @@ watch(() => props.modelValue, (open) => {
             form.description = ''
             form.color = '#222783'
             form.clientId = null
+            form.workflowId = defaultWorkflowId()
             form.giteaRepoFullName = null
             form.bookstackShelfId = null
         }
@@ -269,6 +291,9 @@ async function handleSubmit() {
             await update(props.project.id, payload)
         } else {
             payload.code = form.code
+            if (form.workflowId) {
+                payload.workflow = `/api/workflows/${form.workflowId}`
+            }
             await create(payload)
         }
 
@@ -308,6 +333,15 @@ async function handleArchiveToggle() {
 }
 
 onMounted(async () => {
+    try {
+        workflows.value = await getAllWorkflows()
+        // Si le drawer est déjà ouvert en création, pré-remplir une fois les workflows chargés.
+        if (props.modelValue && !props.project && !form.workflowId) {
+            form.workflowId = defaultWorkflowId()
+        }
+    } catch {
+        // Workflows indisponibles, ignore (le serveur assignera le défaut)
+    }
     try {
         giteaRepos.value = await listRepositories()
     } catch {
diff --git a/src/Module/ProjectManagement/Domain/Entity/Project.php b/src/Module/ProjectManagement/Domain/Entity/Project.php
index b788704..2ebe666 100644
--- a/src/Module/ProjectManagement/Domain/Entity/Project.php
+++ b/src/Module/ProjectManagement/Domain/Entity/Project.php
@@ -92,10 +92,11 @@ class Project implements ProjectInterface, TimestampableInterface, BlamableInter
     #[Groups(['project:read', 'project:write'])]
     private ?ClientInterface $client = null;
 
+    // workflow_id reste NOT NULL en base ; quand l'appelant n'en fournit pas,
+    // ProjectDefaultWorkflowListener assigne le workflow par défaut au prePersist.
     #[ORM\ManyToOne(targetEntity: Workflow::class)]
     #[ORM\JoinColumn(nullable: false, onDelete: 'RESTRICT')]
     #[Groups(['project:read', 'project:write', 'task:read'])]
-    #[Assert\NotNull(message: 'Un projet doit avoir un workflow.')]
     private ?Workflow $workflow = null;
 
     #[ORM\Column(length: 255, nullable: true)]
diff --git a/src/Module/ProjectManagement/Infrastructure/EventListener/ProjectDefaultWorkflowListener.php b/src/Module/ProjectManagement/Infrastructure/EventListener/ProjectDefaultWorkflowListener.php
new file mode 100644
index 0000000..f4c26fd
--- /dev/null
+++ b/src/Module/ProjectManagement/Infrastructure/EventListener/ProjectDefaultWorkflowListener.php
@@ -0,0 +1,36 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Module\ProjectManagement\Infrastructure\EventListener;
+
+use App\Module\ProjectManagement\Domain\Entity\Project;
+use App\Module\ProjectManagement\Domain\Repository\WorkflowRepositoryInterface;
+use Doctrine\ORM\Event\PrePersistEventArgs;
+use RuntimeException;
+
+/**
+ * Assigns the default workflow to a project when none was provided.
+ * Guarantees the NOT NULL workflow_id constraint across every persistence
+ * path (API Platform, raw API, MCP) without forcing the caller to supply one.
+ */
+final readonly class ProjectDefaultWorkflowListener
+{
+    public function __construct(private WorkflowRepositoryInterface $workflowRepository) {}
+
+    public function prePersist(Project $project, PrePersistEventArgs $args): void
+    {
+        if (null !== $project->getWorkflow()) {
+            return;
+        }
+
+        $default = $this->workflowRepository->findDefault()
+            ?? ($this->workflowRepository->findBy([], ['position' => 'ASC'], 1)[0] ?? null);
+
+        if (null === $default) {
+            throw new RuntimeException('Cannot create a project: no workflow exists. Seed at least one workflow first.');
+        }
+
+        $project->setWorkflow($default);
+    }
+}
diff --git a/src/Module/ProjectManagement/Infrastructure/Mcp/Tool/Project/CreateProjectTool.php b/src/Module/ProjectManagement/Infrastructure/Mcp/Tool/Project/CreateProjectTool.php
index a423644..4d522e5 100644
--- a/src/Module/ProjectManagement/Infrastructure/Mcp/Tool/Project/CreateProjectTool.php
+++ b/src/Module/ProjectManagement/Infrastructure/Mcp/Tool/Project/CreateProjectTool.php
@@ -6,6 +6,7 @@ namespace App\Module\ProjectManagement\Infrastructure\Mcp\Tool\Project;
 
 use App\Module\Directory\Domain\Repository\ClientRepositoryInterface;
 use App\Module\ProjectManagement\Domain\Entity\Project;
+use App\Module\ProjectManagement\Domain\Repository\WorkflowRepositoryInterface;
 use App\Shared\Infrastructure\Mcp\Serializer;
 use Doctrine\ORM\EntityManagerInterface;
 use InvalidArgumentException;
@@ -15,12 +16,13 @@ use Symfony\Component\Security\Core\Exception\AccessDeniedException;
 
 use function sprintf;
 
-#[McpTool(name: 'create-project', description: 'Create a new project. Code must be 2-10 uppercase letters.')]
+#[McpTool(name: 'create-project', description: 'Create a new project. Code must be 2-10 uppercase letters. Optional workflowId selects the kanban workflow; the default workflow is used when omitted.')]
 class CreateProjectTool
 {
     public function __construct(
         private readonly EntityManagerInterface $entityManager,
         private readonly ClientRepositoryInterface $clientRepository,
+        private readonly WorkflowRepositoryInterface $workflowRepository,
         private readonly Security $security,
     ) {}
 
@@ -30,6 +32,7 @@ class CreateProjectTool
         ?string $description = null,
         ?string $color = null,
         ?int $clientId = null,
+        ?int $workflowId = null,
     ): string {
         if (!$this->security->isGranted('ROLE_USER')) {
             throw new AccessDeniedException('Access denied: ROLE_USER required.');
@@ -52,6 +55,14 @@ class CreateProjectTool
             }
             $project->setClient($client);
         }
+        if (null !== $workflowId) {
+            $workflow = $this->workflowRepository->findById($workflowId);
+            if (null === $workflow) {
+                throw new InvalidArgumentException(sprintf('Workflow with ID %d not found.', $workflowId));
+            }
+            $project->setWorkflow($workflow);
+        }
+        // When no workflow is supplied, ProjectDefaultWorkflowListener assigns the default at prePersist.
 
         $this->entityManager->persist($project);
         $this->entityManager->flush();
diff --git a/tests/Functional/Module/ProjectManagement/ProjectCreationWorkflowTest.php b/tests/Functional/Module/ProjectManagement/ProjectCreationWorkflowTest.php
new file mode 100644
index 0000000..8f47f76
--- /dev/null
+++ b/tests/Functional/Module/ProjectManagement/ProjectCreationWorkflowTest.php
@@ -0,0 +1,92 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Tests\Functional\Module\ProjectManagement;
+
+use App\Module\Core\Domain\Entity\Permission;
+use App\Module\Core\Domain\Entity\User;
+use App\Module\ProjectManagement\Domain\Entity\Workflow;
+use App\Module\ProjectManagement\Domain\Repository\WorkflowRepositoryInterface;
+use Doctrine\ORM\EntityManagerInterface;
+use Symfony\Bundle\FrameworkBundle\Test\WebTestCase;
+
+/**
+ * Vérifie que la création d'un projet fonctionne avec ou sans workflow fourni :
+ * - sans workflow → le workflow par défaut est assigné par le listener prePersist
+ * - avec workflow → le workflow choisi est conservé.
+ *
+ * @internal
+ */
+final class ProjectCreationWorkflowTest extends WebTestCase
+{
+    public function testCreateProjectWithoutWorkflowAssignsDefault(): void
+    {
+        $client = self::createClient();
+        $em     = self::getContainer()->get(EntityManagerInterface::class);
+
+        $client->loginUser($this->createManager($em));
+
+        $client->request('POST', '/api/projects', server: [
+            'CONTENT_TYPE' => 'application/ld+json',
+        ], content: json_encode([
+            'code' => $this->randomCode(),
+            'name' => 'Projet sans workflow',
+        ]));
+
+        self::assertResponseStatusCodeSame(201);
+        $data = json_decode($client->getResponse()->getContent(), true);
+        self::assertArrayHasKey('workflow', $data);
+        self::assertNotNull($data['workflow'], 'Un workflow par défaut doit avoir été assigné.');
+    }
+
+    public function testCreateProjectWithExplicitWorkflow(): void
+    {
+        $client = self::createClient();
+        $em     = self::getContainer()->get(EntityManagerInterface::class);
+
+        $workflow = self::getContainer()->get(WorkflowRepositoryInterface::class)->findDefault()
+            ?? $em->getRepository(Workflow::class)->findOneBy([]);
+        self::assertInstanceOf(Workflow::class, $workflow, 'Les fixtures doivent fournir au moins un workflow.');
+
+        $client->loginUser($this->createManager($em));
+
+        $client->request('POST', '/api/projects', server: [
+            'CONTENT_TYPE' => 'application/ld+json',
+        ], content: json_encode([
+            'code'     => $this->randomCode(),
+            'name'     => 'Projet avec workflow',
+            'workflow' => '/api/workflows/'.$workflow->getId(),
+        ]));
+
+        self::assertResponseStatusCodeSame(201);
+        $data = json_decode($client->getResponse()->getContent(), true);
+        self::assertSame($workflow->getId(), $data['workflow']['id'] ?? null);
+    }
+
+    private function createManager(EntityManagerInterface $em): User
+    {
+        $permission = $em->getRepository(Permission::class)->findOneBy(['code' => 'project-management.projects.manage']);
+        self::assertInstanceOf(Permission::class, $permission, 'Lancer app:sync-permissions pour project-management.projects.manage.');
+
+        $user = new User();
+        $user->setUsername('proj-create-'.uniqid());
+        $user->setPassword('x');
+        $user->setRoles(['ROLE_USER']);
+        $user->addDirectPermission($permission);
+        $em->persist($user);
+        $em->flush();
+
+        return $user;
+    }
+
+    private function randomCode(): string
+    {
+        $letters = '';
+        for ($i = 0; $i < 6; ++$i) {
+            $letters .= chr(random_int(65, 90));
+        }
+
+        return $letters;
+    }
+}