Diop was traded by Dallas for the second time in less than a year. He had gone to the New Jersey Nets but the Mavs got him back again during the off-season.
"We want to thank DeSagana," Dallas General Manager Donnie Nelson said. "He is hands-down one of the classiest people I have ever known. His contributions both on and off the court will certainly be missed. The Mavericks' family wishes him nothing but the very best."
Diop has averaged 1.6 points and 3.5 rebounds in 34 games this season.
Carroll, a 40.3 percent 3-point shooter in his NBA career, has had an average of just 4.1 points a game for the Bobcats this season. Hollins has averaged 2.6 points and 1.7 rebounds for Charlotte.
"We are excited to add two young talents in Matt and Ryan to our roster," Nelson said.
Charlotte GM Rod Higgins said Diop "is a nice complement to our roster and someone we feel will add size, dept and experience to our power positions."