The Chicago Bears announced Trevathan has agreed to a four-year deal.
Trevathan, in his fifth year, played three seasons for the Broncos and will be reunited with former Broncos head coach John Fox.
Trevathan missed much of the 2014 season with a series of injuries to his left leg, but had a stellar comeback in 2015 and led the team with 109 tackles. He started every game but one and also started in every postseason game.
Todd Davis was Trevathan’s backup last season and should be considered in the mix to start next season.