Chavez will start Thursday's game against the Reds, Bobby Nightengale of The Cincinnati Enquirer reports.
Chavez was let go by the Angels in late March, but he signed a minor-league deal with Atlanta in April and began the season with Triple-A Gwinnett. The 37-year-old posted a 2.25 ERA and 1.00 WHIP in 20 innings across 13 relief appearances, and he'll make a spot start Thursday. Since the right-hander has only pitched out of the bullpen across the past two seasons, Atlanta could rely heavily on its bullpen in Thursday's matchup.