The Rockies selected Gilbreath's contract from Triple-A Albuquerque on Friday.
Gilbreath was booted off the 40-man roster back in April but has managed to return to the majors despite a 6.21 ERA and 37:20 K:BB over 37.2 innings with Albuquerque. He'll give interim manager Warren Schaeffer another lefty arm in the bullpen.