The qualifying offer of $4.2 million to Henderson will allow the Bobcats to match any offer he receives from another team.
The Bobcats decided not to extend Mullens a $3.2 million qualifying offer. Mullens becomes a free agent.
Charlotte selected Henderson with the 12th overall pick in the 2009 draft. He's coming off his best season, averaging a career-high 15.5 points, 3.7 rebounds, 2.6 assists and one steal in 31.4 minutes per game.
Mullens played in 53 games last season, averaging 10.6 points and 6.4 rebounds in 26.9 minutes per game.