The Red Sox selected Penrod's contract from Triple-A Worcester on Saturday, Julian McWilliams of The Boston Globe reports.
After starting the season at Double-A Portland, Penrod will now get his first taste of the big leagues. The 27-year-old southpaw owns a 5.93 ERA and 1.70 WHIP through 27.1 innings at Triple-A, however, so he will likely be limited to low-leverage situations while with the Red Sox.