The Mets selected Herget's contract from Triple-A Syracuse on Saturday.
Herget will join the big club for the first time this season after spending the first portion of the year working his way back from an injury. He's given up six earned runs over 13.1 innings while pitching at four different levels and will presumably work in middle relief while with the Mets. Xzavion Curry was optioned to Triple-A in a corresponding move.