diff --git a/flask_admin/base.py b/flask_admin/base.py
index 760b73fe0..487bcbd2a 100644
--- a/flask_admin/base.py
+++ b/flask_admin/base.py
@@ -598,6 +598,8 @@ def __init__(
         # Register with application
         if app is not None:
             self._init_extension()
+            # Make theme available via current_app
+            app.config["theme"] = self.theme
 
     def _validate_admin_host_and_subdomain(self):
         if self.subdomain is not None and self.host is not None:
diff --git a/flask_admin/form/widgets.py b/flask_admin/form/widgets.py
index 495066206..9f67aebee 100644
--- a/flask_admin/form/widgets.py
+++ b/flask_admin/form/widgets.py
@@ -108,6 +108,7 @@ def __call__(self, field, **kwargs):
                 "_gettext": gettext,
                 "_ngettext": ngettext,
                 "h": h,
+                "theme": current_app.config["theme"],
             }
         )