diff --git a/cinder/tests/unit/volume/drivers/dell_emc/unity/fake_exception.py b/cinder/tests/unit/volume/drivers/dell_emc/unity/fake_exception.py
index 3f7f3fccee4..cd415decde6 100644
--- a/cinder/tests/unit/volume/drivers/dell_emc/unity/fake_exception.py
+++ b/cinder/tests/unit/volume/drivers/dell_emc/unity/fake_exception.py
@@ -58,6 +58,14 @@ class DetachIsCalled(Exception):
     pass
 
 
+class DetachAllIsCalled(Exception):
+    pass
+
+
+class DetachFromIsCalled(Exception):
+    pass
+
+
 class LunDeleteIsCalled(Exception):
     pass
 
diff --git a/cinder/tests/unit/volume/drivers/dell_emc/unity/test_adapter.py b/cinder/tests/unit/volume/drivers/dell_emc/unity/test_adapter.py
index e871a353a50..fbf809a0278 100644
--- a/cinder/tests/unit/volume/drivers/dell_emc/unity/test_adapter.py
+++ b/cinder/tests/unit/volume/drivers/dell_emc/unity/test_adapter.py
@@ -140,6 +140,12 @@ class MockClient(object):
         if host.name == 'host1' and lun_or_snap.get_id() in error_ids:
             raise ex.DetachIsCalled()
 
+    @staticmethod
+    def detach_all(lun):
+        error_ids = ['lun_44']
+        if lun.get_id() in error_ids:
+            raise ex.DetachAllIsCalled()
+
     @staticmethod
     def get_iscsi_target_info(allowed_ports=None):
         return [{'portal': '1.2.3.4:1234', 'iqn': 'iqn.1-1.com.e:c.a.a0'},
@@ -443,6 +449,13 @@ class CommonAdapterTest(test.TestCase):
 
         self.assertRaises(ex.DetachIsCalled, f)
 
+    def test_terminate_connection_force_detach(self):
+        def f():
+            volume = MockOSResource(provider_location='id^lun_44', id='id_44')
+            self.adapter.terminate_connection(volume, None)
+
+        self.assertRaises(ex.DetachAllIsCalled, f)
+
     def test_terminate_connection_snapshot(self):
         def f():
             connector = {'host': 'host1'}
diff --git a/cinder/tests/unit/volume/drivers/dell_emc/unity/test_client.py b/cinder/tests/unit/volume/drivers/dell_emc/unity/test_client.py
index 5c623ab9857..f65b45cab22 100644
--- a/cinder/tests/unit/volume/drivers/dell_emc/unity/test_client.py
+++ b/cinder/tests/unit/volume/drivers/dell_emc/unity/test_client.py
@@ -100,6 +100,11 @@ class MockResource(object):
         if lun_or_snap.name == 'detach_failure':
             raise ex.DetachIsCalled()
 
+    @staticmethod
+    def detach_from(host):
+        if host is None:
+            raise ex.DetachFromIsCalled()
+
     def get_hlu(self, lun):
         return self.alu_hlu_map.get(lun.get_id(), None)
 
@@ -446,6 +451,13 @@ class ClientTest(unittest.TestCase):
 
         self.assertRaises(ex.DetachIsCalled, f)
 
+    def test_detach_all(self):
+        def f():
+            lun = MockResource('lun_44')
+            self.client.detach_all(lun)
+
+        self.assertRaises(ex.DetachFromIsCalled, f)
+
     @mock.patch.object(coordination.Coordinator, 'get_lock')
     def test_create_host(self, fake):
         self.assertEqual('host2', self.client.create_host('host2').name)
diff --git a/cinder/volume/drivers/dell_emc/unity/adapter.py b/cinder/volume/drivers/dell_emc/unity/adapter.py
index 087fcfffa49..a1dd12023bc 100644
--- a/cinder/volume/drivers/dell_emc/unity/adapter.py
+++ b/cinder/volume/drivers/dell_emc/unity/adapter.py
@@ -312,8 +312,12 @@ class CommonAdapter(object):
         return self._initialize_connection(lun, connector, volume.id)
 
     def _terminate_connection(self, lun_or_snap, connector):
-        host = self.client.create_host(connector['host'])
-        self.client.detach(host, lun_or_snap)
+        is_force_detach = connector is None
+        if is_force_detach:
+            self.client.detach_all(lun_or_snap)
+        else:
+            host = self.client.create_host(connector['host'])
+            self.client.detach(host, lun_or_snap)
 
     @cinder_utils.trace
     def terminate_connection(self, volume, connector):
diff --git a/cinder/volume/drivers/dell_emc/unity/client.py b/cinder/volume/drivers/dell_emc/unity/client.py
index c7599bbaa2b..880d1259cb7 100644
--- a/cinder/volume/drivers/dell_emc/unity/client.py
+++ b/cinder/volume/drivers/dell_emc/unity/client.py
@@ -253,6 +253,15 @@ class UnityClient(object):
         lun_or_snap.update()
         host.detach(lun_or_snap)
 
+    @staticmethod
+    def detach_all(lun):
+        """Detaches a `UnityLun` from all hosts.
+
+        :param lun: `UnityLun` object
+        """
+        lun.update()
+        lun.detach_from(host=None)
+
     def get_ethernet_ports(self):
         return self.system.get_ethernet_port()
 
diff --git a/doc/source/configuration/block-storage/drivers/dell-emc-unity-driver.rst b/doc/source/configuration/block-storage/drivers/dell-emc-unity-driver.rst
index 0e71d93446f..09008aabef0 100644
--- a/doc/source/configuration/block-storage/drivers/dell-emc-unity-driver.rst
+++ b/doc/source/configuration/block-storage/drivers/dell-emc-unity-driver.rst
@@ -301,6 +301,14 @@ For data path, please follow below steps:
 - If you create a volume using Cinder and attach it to a VM,
   the connection between this VM and volume will be IPv6-based iSCSI.
 
+Force detach volume from all hosts
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The user could use `os-force_detach` action to detach a volume from all its
+attached hosts.
+For more detail, please refer to
+https://developer.openstack.org/api-ref/block-storage/v2/?expanded=force-detach-volume-detail#force-detach-volume
+
 Troubleshooting
 ~~~~~~~~~~~~~~~
 
diff --git a/releasenotes/notes/unity-force-detach-7c89e72105f9de61.yaml b/releasenotes/notes/unity-force-detach-7c89e72105f9de61.yaml
new file mode 100644
index 00000000000..2a885fd7e5b
--- /dev/null
+++ b/releasenotes/notes/unity-force-detach-7c89e72105f9de61.yaml
@@ -0,0 +1,4 @@
+---
+features:
+  - |
+    Add support to force detach a volume from all hosts on Unity.