The Rangers recalled Pennington from Triple-A Round Rock on Sunday.
Pennington will replace fellow left-hander Brock Burke in the Texas bullpen after the Rangers designated Burke for assignment. Acquired from the Royals on July 29 in the deal that sent right-hander Michael Lorenzen to Kansas City, Pennington previously made his Rangers debut last Sunday against the Red Sox, working one inning while giving up an earned run on one hit and three walks. He'll likely occupy a low-leverage role during his upcoming stint with Texas.