The Marlins recalled Okert from Triple-A Jacksonville on Tuesday, Jordan McPherson of the Miami Herald reports.
The lefty reliever has impressed at Triple-A this season, pitching to a 1.80 ERA in 20 innings while striking out 29 batters and walking just one while allowing just a single homer. He last appeared in the majors in 2018, when he pitched in seven games for the Giants and posted a 1.23 ERA.