Williams appeared in Homicide: Life on the Street, a show based on a book by The Wire creator David Simon, where he guest-starred as Casper in the episode "The Why Chromosome".[6] He had a small guest starring role in The Sopranos episode "46 Long" as Special K, an incompetent stickup man and one of Brendan Filone's goons.[5] He went on to play series regular, inmate Kenny Wangler, in the first four seasons of Oz.[7] He then appeared in HBOs The Wire as Bodie Broadus, a Barksdale Organization drug dealer who slowly rises through the ranks throughout the seasons.[7][8] In preparation for the role, he walked around Baltimore's inner city during the middle of the night a few days before the first taping; talking about this to AllHipHop, Williams stated "it was like 12 or 1:00 in the morning. I just threw on a black hoodie and walked around. I went to one of their hoods and watched that night. I learned not to do that no more, I was lucky I made it back that night."[5] He is older than his character by eight years.[4]
According to his original HBO bio, he is credited with appearing in the film Graffiti Bridge, but a 2003 interview with AllHipHop revealed that Williams was not in the movie.[5] The page no longer exists, however. Tevin Campbell filled the cameo role with which Williams was credited.
Williams has had leading roles or cameo appearances in a number of R&B and hip-hopmusic videos. He has appeared as himself, a love interest, and characters resembling his role as a drug dealer on The Wire.[4][5]
In 2012, Williams had a major supporting role in the indie film Surviving Family as the ex-boyfriend of the main character. His character was a wounded veteran of the war in Iraq who had lost an eye in an IED attack and suffered from PTSD.
He has starred in a number of commercials, and played a delivery man in a FedEx commercial.[9] He appeared as Lemond Bishop's Lieutenant "Dexter" in episodes of The Good Wife.