Starred in the sketch comedy show MADtv, from the fourth season (1998) and remained in the cast until the end of the thirteenth and penultimate season. While on the show, he developed many memorable characters. He was a contributing writer and director on MADtv.

McDonald also directed several episodes of the comedy-drama series Scrubs, on which he guest-starred six times.

McDonald currently divides his time between writing, directing, and acting on various film and television projects, as well as performing live on stage across the country.