Gilliam spent the past two seasons as a backup swing tackle for the 49ers before the team decided to let him go Wednesday. Gilliam could have made $5.05 million this season for San Francisco.
The Niners originally signed him as a free agent in 2017 and then re-signed him to a two-year contract last year. Gilliam played in 24 games with one start in two seasons with San Francisco.
Gilliam spent his first three seasons with Seattle.