The two stars met on the set of X-Men: First Class in 2011, but their relationship came to an end late last year (12).
The split came shortly before they were both announced in the cast for the follow-up film, X-Men: Days of Future Past, which is due to begin filming later this year (13).
Hoult has now insisted they will remain professional when they are called to work together again.
Asked whether the movie will be awkward for the former lovers, Hoult tells the London Evening Standard, "No, not at all. We had a great time making that first film..."
The actor is also asked whether he feels "weird" seeing his ex-girlfriend voted among the sexiest women in the world, and he adds, "No, because I know her. I never really get starstruck by actors."