You may be interested by the host requirements in the routing file, take a look : http://symfony.com/doc/current/book/routing.html#adding-a-host-requirement
That means you can scope an entire bundle routing to a certain domain.
Don't specify host requirement to your fos user routing, it will works for every domains. Then override the login/register/... templates for each domain. You may need to override the controllers too. https://github.com/FriendsOfSymfony/FOSUserBundle/blob/master/Resources/doc/overriding_controllers.md https://github.com/FriendsOfSymfony/FOSUserBundle/blob/master/Resources/doc/overriding_templates.md