The original-round tender will cost the Steelers around $1.797 million for the 2017 season and give them the right of first refusal for any offer sheet he receives from another team during free agency.
Gilliam, 26, wound up signing on with the Seahawks as an undrafted free agent out of Penn State back in 2014. He managed to make the 53-man roster during his rookie season has been on their active roster ever since.
In 2016, Gilliam appeared in 14 games for the Seahawks and was rated by Pro Football Focus as the No. 71 offensive tackle out of 78 qualifying players.