diff --git a/pymisp/api.py b/pymisp/api.py
index d361eb7..033d43f 100644
--- a/pymisp/api.py
+++ b/pymisp/api.py
@@ -771,6 +771,40 @@ class PyMISP:
 
     # ## END Analyst Relationship ###
 
+    # ## BEGIN Galaxy Cluster ###
+    def attach_galaxy_cluster(self, misp_entity: MISPEvent | MISPAttribute, galaxy_cluster: MISPGalaxyCluster | int | str, local: bool = False, pythonify: bool = False) -> dict[str, Any] | list[dict[str, Any]]:
+        """Attach a galaxy cluster to an event or an attribute
+
+        :param misp_entity: a MISP Event or a MISP Attribute
+        :param galaxy_cluster: Galaxy cluster to attach
+        :param local: whether the object should be attached locally or not to the target
+        :param pythonify: Returns a PyMISP Object instead of the plain json output
+        """
+        if isinstance(misp_entity, MISPEvent):
+            attach_target_type = 'event'
+        elif isinstance(misp_entity, MISPAttribute):
+            attach_target_type = 'attribute'
+        else:
+            raise PyMISPError('The misp_entity must be MISPEvent or MISPAttribute')
+
+        attach_target_id = misp_entity.id
+        local = 1 if local else 0
+
+        if isinstance(galaxy_cluster, MISPGalaxyCluster):
+            cluster_id = galaxy_cluster.id
+        elif isinstance(galaxy_cluster, (int, str)):
+            cluster_id = galaxy_cluster
+        else:
+            raise PyMISPError('The galaxy_cluster must be MISPGalaxyCluster or the id associated with the cluster (int or str)')  
+
+        to_post = { 'Galaxy': { 'target_id': cluster_id } }
+        url = f'galaxies/attachCluster/{attach_target_id}/{attach_target_type}/local:{local}'
+
+        r = self._prepare_request('POST', url, data=to_post)
+        return self._check_json_response(r)
+    # ## END Galaxy Cluster ###
+
+
     # ## BEGIN Object ###
 
     def get_object(self, misp_object: MISPObject | int | str | UUID, pythonify: bool = False) -> dict[str, Any] | MISPObject:
diff --git a/tests/testlive_comprehensive.py b/tests/testlive_comprehensive.py
index 2c33b29..6f33db4 100644
--- a/tests/testlive_comprehensive.py
+++ b/tests/testlive_comprehensive.py
@@ -3198,6 +3198,7 @@ class TestComprehensive(unittest.TestCase):
             self.admin_misp_connector.delete_event(event)
             self.admin_misp_connector.toggle_global_pythonify()
 
+
     def test_analyst_data_CRUD(self) -> None:
         event = self.create_simple_event()
         self.admin_misp_connector.toggle_global_pythonify()
@@ -3334,6 +3335,43 @@ class TestComprehensive(unittest.TestCase):
             except Exception:
                 pass
 
+    def test_attach_galaxy_cluster(self) -> None:
+        event = self.create_simple_event() 
+        event = self.admin_misp_connector.add_event(event, pythonify=True)
+        try:
+            galaxies: list[MISPGalaxy] = self.admin_misp_connector.galaxies(pythonify=True)
+            galaxy: MISPGalaxy = galaxies[0]
+            if gid := galaxy.id:
+                galaxy = self.admin_misp_connector.get_galaxy(gid, withCluster=True, pythonify=True)
+            else:
+                raise Exception("No galaxy found")
+            galaxy_cluster: MISPGalaxyCluster = galaxy.clusters[0]
+            self.admin_misp_connector.attach_galaxy_cluster(event, galaxy_cluster)
+            event = self.admin_misp_connector.get_event(event.id, pythonify=True)
+
+            self.assertEqual(len(event.galaxies), 1)
+            event_galaxy = event.galaxies[0]
+            # The galaxy ID should equal the galaxy from which the cluster came from
+            self.assertEqual(event_galaxy.id, galaxy.id)
+            # The galaxy cluster should equal the cluster added
+            self.assertEqual(event_galaxy.clusters[0].id, galaxy_cluster.id)
+
+            galaxy_cluster: MISPGalaxyCluster = galaxy.clusters[1]
+
+            # Test on attribute
+            attribute = event.Attribute[0]
+            event = self.admin_misp_connector.get_event(event.id, pythonify=True)
+            attribute = event.Attribute[0]
+            self.assertEqual(len(attribute.galaxies), 1)
+            attribute_galaxy = attribute.galaxies[0]
+            # The galaxy ID should equal the galaxy from which the cluster came from
+            self.assertEqual(attribute_galaxy.id, galaxy.id)
+            # The galaxy cluster should equal the cluster added
+            self.assertEqual(attribute_galaxy.clusters[0].id, galaxy_cluster.id)
+        finally:
+            self.admin_misp_connector.delete_event(event)
+            self.admin_misp_connector.toggle_global_pythonify()
+
     @unittest.skip("Internal use only")
     def missing_methods(self) -> None:
         skip = [