Bell, 29, struggled with injuries throughout the 2015 season and was passed on the depth chart by rookie Ameer Abdullah and Theo Riddick. He gained a career-low 311 yards on 90 carries with four touchdowns.
Bell played five seasons for Detroit after bouncing around the league as an undrafted free agent out of Wayne State early in his career. He landed with Detroit in 2011 and spent the next four seasons having a large role with the franchise, including a team-best 860 yards in 2014.
In 68 career games, all but eight with Detroit, he rushed 561 times for 2,235 yards and 22 touchdowns. He also had 161 receptions for 1,640 yards and a touchdown.
Bell's release gives Detroit $2.5 million in cap space. He'll be on the books for $1 million in dead money in 2016.