Before his debut on Scrubs, Faison became famous for his role as "Murray Lawrence Duvall" in Clueless, the 1995 movie, and its subsequent television series, which ran from 1996 to 1999. In 1995, he also appeared in Waiting to Exhale as "Tarik", the son of Loretta Devine's character, "Gloria." He was also featured in the hood film New Jersey Drive. He had a recurring role as, "Tracy," on Felicity, appeared in Remember the Titans, as the back-up running back, "Petey," He had minor roles in the sitcoms Sister Sister and Sabrina, the Teenage Witch, in the film Josie and the Pussycats and provided voice work for various characters in the MTV animated series Clone High and Cartoon Network's Robot Chicken.
In the Robot Chicken: Star Wars Special DVD Commentary, Faison admitted that he wanted to learn how to create Stop Motion animation. The crew of Robot Chicken said they would help in any way; but, Faison said he couldn't do it, because they were too far away, and he was busy with Scrubs.
In 2009, Donald joined the Titan Maximum cast.