Overton will start Thursday's game against the Reds, Kevin Gorman of TribLive.com reports.
Overton pitched one inning out of the bullpen Sunday after being claimed off waivers by Pittsburgh, and he'll now make his first big-league start Thursday. The 28-year-old isn't fully built up and is unlikely to have the workload of a traditional starter. He has yet to allow a run through his first 7.2 frames in the majors.