diff --git a/lemarche/siaes/models.py b/lemarche/siaes/models.py
index bfa284c54..24a16fdee 100644
--- a/lemarche/siaes/models.py
+++ b/lemarche/siaes/models.py
@@ -6,6 +6,7 @@
 from django.contrib.gis.db.models.functions import Distance
 from django.contrib.gis.measure import D
 from django.contrib.postgres.search import TrigramSimilarity  # SearchVector
+from django.core.exceptions import ValidationError
 from django.db import IntegrityError, models, transaction
 from django.db.models import (
     BooleanField,
@@ -1279,6 +1280,18 @@ def set_super_badge(self):
 
         self.save(update_fields=update_fields_list)
 
+    def clean(self):
+        """
+        Validate that brand is not used as a brand or name by another Siae
+        Does not use a unique constraint on model because it allows blank values and checks two fields simultaneously.
+        """
+        super().clean()
+        if self.brand:
+            # Check if brand is used as name by another Siae
+            name_exists = Siae.objects.exclude(id=self.id).filter(Q(name=self.brand) | Q(brand=self.brand)).exists()
+            if name_exists:
+                raise ValidationError({"brand": "Ce nom commercial est déjà utilisé par une autre structure."})
+
 
 @receiver(post_save, sender=Siae)
 def siae_post_save(sender, instance, **kwargs):
diff --git a/lemarche/www/dashboard_siaes/tests.py b/lemarche/www/dashboard_siaes/tests.py
index f6fae991d..4346c968e 100644
--- a/lemarche/www/dashboard_siaes/tests.py
+++ b/lemarche/www/dashboard_siaes/tests.py
@@ -193,6 +193,19 @@ def test_siae_edit_info_form(self):
         self.assertEqual(self.siae_with_user.brand, "Nouveau nom commercial")
         self.assertEqual(self.siae_with_user.name_display, "Nouveau nom commercial")
 
+    def test_siae_edit_info_form_brand_unique(self):
+        SiaeFactory(brand="Nouveau nom commercial")
+
+        self.client.force_login(self.user_siae)
+        url = reverse("dashboard_siaes:siae_edit_info", args=[self.siae_with_user.slug])
+
+        data = {
+            "brand": "Nouveau nom commercial",
+        }
+        response = self.client.post(url, data=data)
+        self.assertEqual(response.status_code, 200)
+        self.assertContains(response, "Ce nom commercial est déjà utilisé par une autre structure.")
+
 
 class DashboardSiaeUserViewTest(TestCase):
     @classmethod