Weller was initially successful as a stage actor, and stage acting is still his biggest passion. He performed in Neil LaBute and David Mamet plays and films.
Weller has also played lead roles in many successful independent films, including Neil Labute's The Shape of Things (with Paul Rudd and Rachel Weisz), James Tobak's When Will I Be Loved (opposite Neve Campbell) and The Business of Strangers (with Stockard Channing and Julia Stiles).