The Pirates selected Sullivan's contract from Triple-A Indianapolis on Saturday.
With Endy Rodriguez (elbow) placed on the 10-day injured list and Joey Bart still in the concussion protocol, Sullivan will be brought up to serve as the Pirates' backup catcher behind Henry Davis. Sullivan was acquired by the Pirates in April from the Padres, and he has a .211/.350/.324 with two steals, one home run and 10 RBI across 76 plate appearances with Indianapolis.