The Jaguars signed Thornhill to their practice squad Monday.
The 30-year-old safety was dropped by the Steelers on Nov. 10 but has quickly found a new home in Jacksonville. Thornhill appeared in nine games for the Steelers this season, recording 38 total tackles and one pass defended across 313 defensive snaps. He could be elevated to the Jaguars' active roster and play a depth role in the team's secondary as the season progresses.