These two moves will account for $13.5 million in salary-cap space for the Bears in 2020.
Gabriel, 29, had 29 receptions for 353 yards and four touchdowns for the Bears last season.
A six-year veteran, he spent two seasons with the Cleveland Browns, two with the Atlanta Falcons and the past two with the Bears.
Amukamara, 30, spent three seasons with the Bears. A first-round draft pick of the New York Giants in 2011, he was part of Super Bowl team there in his rookie year.
After a stint with the Jacksonville Jaguars in 2016, he signed with the Bears in 2017. In March 2018, he signed a three-year, $27 million extension.
Should the Bears pursue Derek Carr?
Bomani Jones and Pablo Torre share their thoughts on whether the Bears should give up draft picks and trade for Derek Carr.