Foltynewicz was drafted in the first round of the 2010 draft. He has since spent parts of six seasons in the minor leagues.
Over 21.2 innings this season with Triple-A Gwinnett, Foltynewicz posted a 2.08 ERA with 30 strikeouts and 10 walks.
MLB.com rated Foltynewicz the Braves' No. 3 prospect in 2015.
Atlanta (10-12) has dropped 11 of its last 15 games.