In 499 games over eight NBA seasons with five teams, the 6-foot-9 Warrick has averaged 9.5 points and 4.1 rebounds with a .494 field-goal percentage.
"We are very excited to add a player of Hakim's ability and overall NBA experience," Bobcats president of basketball operations Rod Higgins said. "His athleticism allows him to play multiple positions, which will make for a smooth transition into our current roster and style of play under coach Mike Dunlap."
Warrick played in only one game this season after being acquired by the Hornets in July.
Carroll, a nine-year NBA veteran, hasn't been in Charlotte's rotation.
Warrick's salary is $4 million this year, and the Bobcats hold a $4 million option for next season. Carroll is earning $3.5 million this season.
The Bobcats are trying to build their team around defense, and Warrick could help in that process.
Warrick, chosen by the Grizzlies with the 19th pick in the 2005 draft, helped Syracuse win the 2003 NCAA tournament championship.
Carroll was acquired by the Bobcats from Dallas in 2010 with Erick Dampier and Eduardo Najera for Tyson Chandler and Alexis Ajinca. In 459 career games with Portland, San Antonio, Charlotte and Dallas, Carroll has averaged 6.6 points and 1.9 rebounds.
Carroll previously played for the Bobcats from 2005-09, and ranks second on the team's career 3-point percentage (.384) and free-throw percentage lists (.841). He is also third with 338 made 3-pointers, and 397 games played.
"Matt Carroll has been a consummate professional both on and off the court during his tenures in Charlotte, and we would like to thank him for everything he added to our franchise," Higgins said.