The Reds promoted Petty from Single-A Daytona to High-A Dayton on Wednesday.
Petty, who was the main piece the Reds received in the March trade that sent Sonny Gray to Minnesota, will advance to Dayton after he submitted a 3.18 ERA, 1.20 WHIP and 60:23 K:BB across 65 innings with Daytona.