Harris signed with the Jaguars as an undrafted free agent last season. He spent much of the year on the practice squad, but was on the Jacksonville active roster for five games. The Jaguars released Harris during their initial round of cuts on Saturday.
In Pittsburgh, Harris will join a running back corps with some injury concerns. Starter Rashard Mendenhall is expected to miss the first few weeks of the season while replacement starter Isaac Redman has battled groin and hip injures this preseason.
Harris is far from a lock to make Pittsburgh's 53-man roster as the Steelers also have Jonathan Dwyer, Chris Rainey and Baron Batch at running back. In limited action for the Jaguars last season, Harris ran for 42 yards on nine carries.