This means that Sitton will be a free agent in the coming weeks.
Sitton, 31, is a former fourth-round pick of the Packers back in 2008. He played eight years for the Packers before they released at the start of the 2016 season.
Sitton later signed a three-year, $21.75 million contract that included $10 million with the Bears. He was set to make a base salary of $7.4 million for the 2018 season.
In 2017, Sitton appeared in 13 games for the Bears and is rated by Pro Football Focus as the No. 5 guard out of 77 qualifying players.