The son of an immigrant from Ghana, Mohammed was raised in Chicago and attended high school at Kenwood Academy. Mohammed entered the University of Kentucky in the fall of 1995 at a hefty 315 pounds, and saw little playing time during their NCAA Championship season. After slimming down for his sophomore year, Mohammed shared the starting center spot with Jamaal Magloire, and was a key contributor in 1997, when the Cats were runners-up to Arizona, and in 1998, when they won another title.

After his junior year, Mohammed was faced with a decision on whether to come back to school or enter the draft, and ultimately decided to enter the 1998 NBA Draft. He was selected by the Utah Jazz in the first round, as the 29th pick overall. Utah traded his rights to the Philadelphia 76ers, with whom he spent two and a half seasons. He then played for the Atlanta Hawks through the middle of the 2004 season, at which point he went to the New York Knicks. Mohammed split the 2004-2005 season between the Knicks and the Spurs (who acquired him in a trade for Malik Rose). In a combined 77 games for both teams, he averaged 9.5 points, 7.6 rebounds, and 1.1 blocks per game. He won the 2005 NBA title with the San Antonio Spurs as a member of their starting lineup.

During Mohammed's second season in San Antonio he shared the starting center position with Nesterovic, averaging 6.2 points and 5.2 rebounds per game during the regular season. He was a key contributor to the team's first round series victory over Sacramento, averaging 7.0 points per game and nailing his second career three-point basket late in Game 1. Mohammed, however, played sparingly in the team's second round series loss to the Dallas Mavericks. After the season, he turned down a four-year contract extension and is not expected to return to the Spurs.