A boomerang works due to it's shape, but not because of aerodynamics.  It's shape is such that there is an instability when thrown correctly, allowing precession.  It is precession that takes the boomerang back to the thrower. The instability can be induced by aerodynamic means, and this type of boomerang would not return to the thrower in outer space.  It would be possible to have a boomerang that doesn't depend on aerodynamics for this instability, for example by having differently-weighted 'arms', and this type would return in space.

When you say 'in space', do you mean in a vacuum, or just in zero G?

if it's been thrown in a space station for instance, then there's still air in there - just very little gravity.

whereas if it's in the vacuum of space, then i'm not aware that it would come back.