Kelly was transported to the south campus of the Atlanta Medical Center around 4:30 p.m. Wednesday after police were called to his home. He was pronounced dead at the hospital at around 5 p.m.
"It appears it may have been a possible drug overdose," said Cpl. Kay Lester, a spokeswoman for the Fulton County police. Lester said that was based on statements received at the scene as well as evidence turned up at Kelly's south Atlanta home.
However, no official cause of death has been determined, pending an autopsy.
Kelly, known as "Mac Daddy," and Chris Smith, known as "Daddy Mac," were introduced to the music world in 1992 by music producer and rapper Jermaine Dupri after he discovered the pair in an Atlanta mall. The duo wore their clothes backwards as a gimmick, but they won over fans with their raps.
"To the world Chris was Mac Daddy but to me, he was a son I never had..." Dupri said in a statement.
"When I think about it, I spent more time with Chris and Chris than damn near anybody in my whole life, so you can imagine how bad this hurts," Dupri added. "I will always love you Chris, and I will never let the world forget you, may God bless your soul."
Their first, and by far most successful song, was "Jump." The hit, off their multiplatinum 1992 debut album "Totally Krossed Out," featured the two trading versus and rapping the refrain, the song's title. The duo had surprising maturity in their rap delivery, though the song was written by Dupri. It would become a No. 1 smash in the United States and globally, and one of the most popular of that year.
Their success led to instant fame: They toured with Michael Jackson, appeared on TV shows, and even had their own video game.
The Associated Press contributed to this report.