diff --git a/magnum/conf/trust.py b/magnum/conf/trust.py
index eb5c826e8b..07e174da8a 100644
--- a/magnum/conf/trust.py
+++ b/magnum/conf/trust.py
@@ -53,7 +53,10 @@ trust_opts = [
                        'by the trustor')),
     cfg.StrOpt('trustee_keystone_interface',
                default='public',
-               help=_('Auth interface used by instances/trustee'))
+               help=_('Auth interface used by instances/trustee')),
+    cfg.StrOpt('trustee_keystone_region_name',
+               help=_('Region in Identity service catalog to use for '
+                      'communication with the OpenStack service.'))
 ]
 
 
diff --git a/magnum/drivers/heat/template_def.py b/magnum/drivers/heat/template_def.py
index 0511a5faa7..397b53c45c 100755
--- a/magnum/drivers/heat/template_def.py
+++ b/magnum/drivers/heat/template_def.py
@@ -255,10 +255,14 @@ class BaseTemplateDefinition(TemplateDefinition):
         else:
             extra_params['trust_id'] = ""
 
-        extra_params['auth_url'] = osc.url_for(
-            service_type='identity',
-            interface=CONF.trust.trustee_keystone_interface,
-            version=3)
+        kwargs = {
+            'service_type': 'identity',
+            'interface': CONF.trust.trustee_keystone_interface,
+            'version': 3
+        }
+        if CONF.trust.trustee_keystone_region_name:
+            kwargs['region_name'] = CONF.trust.trustee_keystone_region_name
+        extra_params['auth_url'] = osc.url_for(**kwargs)
 
         return super(BaseTemplateDefinition,
                      self).get_params(context, cluster_template, cluster,
diff --git a/releasenotes/notes/bug-2002981-trustee-auth-region-name-37796a4e6a274fb8.yaml b/releasenotes/notes/bug-2002981-trustee-auth-region-name-37796a4e6a274fb8.yaml
new file mode 100644
index 0000000000..f465caee19
--- /dev/null
+++ b/releasenotes/notes/bug-2002981-trustee-auth-region-name-37796a4e6a274fb8.yaml
@@ -0,0 +1,8 @@
+---
+fixes:
+  - |
+    Add `trustee_keystone_region_name` optional parameter to the `trust`
+    section. This parameter is useful for multi-regional OpenStack
+    installations with different Identity service for every region.
+    In such installation it is necessary to specify a region when searching
+    for `auth_url` to authenticate a trustee user.