The Steelers signed Gathings to a one-year contract Wednesday, Teresa Varley of the team's official site reports.
Gathings spent time on the Chiefs' practice squad last season and signed a reserve/future deal with Kansas City in February before being cut May 4. The 23-year-old out of Middle Tennessee joins a deep Pittsburgh tight end corps that is headed by Pat Freiermuth, Darnell Washington and Connor Heyward, though that group was relatively unproductive last season.