Early in the third quarter, Burrow was drilled high by Washington defensive end Montez Sweat and hit low by defensive lineman Jonathan Allen while throwing a pass, and his leg bent awkwardly.
Burrow was unable to put any pressure on his leg, which led to him being helped by a cart.
The Bengals held a 9-7 lead over Washington when Burrow was injured. Backup Ryan Finley came in at quarterback for Cincinnati.
Burrow ended his day completing 22 of 34 passes for 203 yards and one touchdown.
Later, Burrow would tweet that he was finished for the season.
Many players around the NFL showed their support for Burrow on social media.
Washington rookie Chase Young was also seen talking to Burrow as he was leaving the field on the cart.
Burrow was among the favorites for Rookie of the Year before the season started.