The 7-foot Mullens was selected by the Mavericks with the 24th pick in the 2009 draft but promptly sent to the Thunder. He's played in only 26 games over the past two seasons while averaging 1.5 points in 5.3 minutes stuck behind Kendrick Perkins, Nazr Mohammed and Cole Aldrich.
The Bobcats hope he can fill the void left by Kwame Brown, who signed with the Warriors.
Bobcats director of basketball operations Rod Higgins said Monday "this is an opportunity where there is a need from our standpoint and there is an opportunity for the player to earn some minutes."
Charlotte hosts Atlanta Monday night in a preseason game.