The linebacker, who was released by the Cleveland Browns before entering his plea, will be sentenced Jan. 24. He faces a maximum of 25 years in prison.
The NFL is currently reviewing Kendricks' legal matter, and the league confirmed he is permitted to sign and participate in team activities, including games, according to NFL Network's Ian Rapoport.
Seattle is currently thin at linebacker, with K.J. Wright dealing with a knee injury, so the veteran defender could see significant snaps in his debut.
Kendricks spent the first six seasons of his career with the Philadelphia Eagles after being selected in the second round in 2012. The 27-year-old posted 77 tackles with two sacks across 15 regular-season appearances in 2017.