A 2012 first-round pick (No. 19 overall) out of Boise State, McClellin played defensive end, outside linebacker and inside linebacker over four years in Chicago.
His best spot appeared to be inside linebacker, where McClellin had a handful of promising moments in Vic Fangio's 3-4 defense in 2015.
"You know, we like Shea," Bears general manager Ryan Pace said. "We feel like his arrow is still pointing up, especially at the inside linebacker position. I thought our defensive coaches did a great job with him."
McClellin, 26, ranked third on the Bears with 81 tackles last season.
ESPN Bears reporter Jeff Dickerson contributed to this report