The 13-year veteran signed a free-agent deal with the Pistons, the team he started his career with in 1995. Ratliff was traded to Philadelphia in 1997 for Jerry Stackhouse, and has also played for Atlanta, Boston, Portland and Minnesota.
"It's great to be back," Ratliff said Tuesday night. "I feel like I'm home again."
Ratliff only played 10 games for Minnesota this season. The Timberwolves agreed to buy out his contract in order let him play for a contender.
"Minnesota was very gracious about working with me, and when Detroit said they wanted me, it was an easy decision," Ratliff said. "I've been on a lot of bad teams, and now I'm at a point in my career where I'm looking to be on a contender."
It helped that Pistons president Joe Dumars and assistant coach Michael Curry are both old teammates of Ratliff's, as is reserve guard Lindsey Hunter.
"Theo will give us a solid veteran presence in the locker room and add depth to our front line," Dumars said. "Having started his career here in Detroit, he understands the culture of our organization and what is expected."
Pistons coach Flip Saunders said that Ratliff could play as soon as Wednesday in Boston.