Steelers signal-caller Ben Roethlisberger gained 81 aerial yards with a touchdown and an interception on 5-of-9 passing.
Jonathan Dwyer rushed for 43 yards rushing on eight carries.
Antonio Brown grabbed a 57-yard TD pass for the Steelers.
The Colts' Andrew Luck threw two interceptions in his second pre-season game, completing 16-of-25 passes for 175 yards. Luck scored on a run.
Reggie Wayne led Indianapolis with six receptions for 74 yards.