The Rockies selected Hartlieb's contract from Triple-A Albuquerque on Saturday.
Hartlieb failed to win a spot on the Rockies out of spring training, but the team will now give him a shot after he put up a 5.61 ERA and 1.66 WHIP through 33.2 innings in Triple-A. The 30-year-old owns a career 7.17 ERA through 70.1 major-league frames and will likely be given only low-leverage situations while with Colorado. Matt Carasiti was designated for assignment in a corresponding move.