VelJohnson is known for playing police officers in films and on television. In Ghostbusters, he had a brief appearance as a Municipal Corrections Officer, and in Crocodile Dundee, he plays a limo driver. VelJohnson played Sgt. Al Powell in the 1988 film Die Hard and later reprised the character in the 1990 sequel Die Hard 2, for which he still received fourth billing. He also portrayed a yelling apartment resident for promoting Instant Lottery games for a Michigan Lottery commercial in 1988. VelJohnson also played a police officer alongside Tom Hanks in Turner & Hooch (1989). Johnson was cast as police officer Carl Winslow in the sitcom Family Matters alongside Jo Marie Payton, who played his wife Harriette Winslow; he starred on that show until 1998. He also had a minor role in the 2002 film Like Mike. VelJohnson reprised his role of Sgt. Al Powell in the GameCube video game title, Die Hard: Vendetta, also in 2002. In 2004, he took the title role in the off-Broadway show She all Dat! (playing "she"). Since the end of Family Matters, besides making a few guest appearances on TV shows, VelJohnson has done mostly theater work. He wrote a critically acclaimed series of short stories called Division Street. One of them, called Sunday Evening Haircut, was made into a short film in 2005, which starred VelJohnson himself, alongside Kiki Shepard. VelJohnson has also made guest appearances in several TV shows, including The Equalizer, Diagnosis: Murder, Twice in a Lifetime, Will & Grace, Monk, CSI: Crime Scene Investigation, Eve, Crossing Jordan, The Parkers, That's So Raven, Chuck, in which he reprises his role as Al Powell, and Bones.