To make roster room for Chacin before Tuesday night's game, the Braves optioned righty Joel De La Cruz back to Gwinnett a day after he was called up.
Chacin joined the Braves' organization as a minor league free agent in December. He is 40-49 with a 3.76 ERA over seven seasons in the majors, the first six with the Colorado Rockies.
Last season, he went 2-1 with a 3.38 ERA in five appearances -- four starts -- for the Arizona Diamondbacks.
Center fielder Mallex Smith was back in the lineup for the Braves on Tuesday, a day after he left his major league debut with a cut on his face that needed five stitches.