The roster moves free up $13.5 million in salary-cap space for the Bears in the 2020 season. Chicago entered Friday with only $5.5 million in cap room.
Gabriel, 29, recorded 29 receptions for 353 yards and four touchdowns with the Bears last season, his second in Chicago. In his first season with the Bears, he had 67 catches for 688 yards and two receiving scores.
Gabriel, a six-year veteran, spent his first two NFL seasons with the Cleveland Browns before joining the Atlanta Falcons. He played in Atlanta for two seasons, posting a career-best six receiving touchdowns in 2016.
The New York Giants selected Amukamara in the first round of the 2011 NFL Draft out of Nebraska. During his rookie season, he was part of the Giants' Super Bowl XLVI-winning team.
Amukamara, 30, spent three seasons with the Bears after a one-year stint with the Jacksonville Jaguars in 2016. He joined the Bears in 2017 and later signed a three-year, $27 million extension with the team in March 2018.
Amukamara posted 53 total tackles, one forced fumble and 10 passes defensed last season. During the 2018 campaign, he recorded 66 combined tackles and tied his career highs in interceptions (three) and forced fumbles (two).