Hawkins, 27, had visited Foxborough for a free-agent workout prior to the opening of training camp.
The 6-foot-6, 305-pound offensive tackle now joins the 90-man roster after a week of transactions that included the release of wide receiver Devin Smith, the placement of tight end Devin Asiasi on the Covid-19 reserve list and the claiming of quarterback Jake Dolegala off waivers.
Hawkins entered the league in the fourth round of the 2016 draft. The LSU product has appeared in 19 games since then, making one start while working back from season-ending shoulder and quad injuries.
The Steelers traded Hawkins to the Tampa Bay Buccaneers in 2019. He later signed with the Houston Texans, beginning 2020 on the practice squad before returning to the organization that once selected him No. 123 overall. Hawkins concluded last campaign having played 76 snaps on offense and five snaps on special teams with Pittsburgh.
In additional movement on Friday, Patriots activated rookie running back Rhamondre Stevenson from the non-football injury list, according to the NFL transaction wire.