The move guarantees a $9.7 million salary for Smith in 2022, per Spotrac.
The No. 8 pick in the 2018 draft has lived up to expectations with the Bears, tallying at least 100 tackles in each of his first three seasons. Smith led the team and finished sixth in the NFL with 139 tackles in 2020.
The 24-year-old added 18 tackles for loss, four sacks and two interceptions and made the All-Pro Second Team.
Chicago took a step back defensively in 2020, finishing 14th in points allowed after ranking in the top five in the category in each of the previous two years. The defense remains as talented as any in the NFL, though, and keeping Smith under contract through 2022 should help it stay among the league's best.
Defensive standouts Khalil Mack, Robert Quinn, Eddie Goldman and Eddie Jackson are also under team control through at least 2023.
While the Bears have question marks offensively, especially at quarterback, the defense should remain a strength.