May, 24, will make his first start in the majors since May 1, 2021, when he suffered a season-ending elbow injury at Milwaukee that required Tommy John surgery.
In five rehab starts with Triple-A Oklahoma City, May went 1-0 with a 1.89 ERA and had 33 strikeouts in 19 innings.
Over his first 31 major league appearances (19 starts), May went 6-5 with a 2.93 ERA with nine games of postseason experience as well. He has faced the Marlins once, giving up a run in 5 2/3 innings of a 2019 win.
Also on Saturday, the Dodgers designated right-hander Reyes Moronta for assignment.
Moronta, 29, recorded a 4.18 ERA without a decision in 22 relief appearances this season.
Moronta is 8-9 with a 2.88 ERA in 158 career relief appearances with the San Francisco Giants (2017-19, 2021) and Dodgers (2022).