TV Guide says that the actor has landed a recurring role on the show's third season.
He is expected to play Ashley, the new boyfriend of Castle's daughter Alexis (Molly Quinn). His first appearance is said to be in the fourth episode.
Castle (Nathan Fillion) is reportedly disappointed when Alexis does not confide in him about the relationship.
Baumann is best known for his role as Ben Boykewich on The Secret Life of the American Teenager.