Waldrop, a first-round pick in 2004, was in uniform for the Twins' game at Texas on Friday night.
Outfielder Matt Carson was optioned to Rochester. Carson hit .381 in five games with the Twins.
It will be Waldrop's second stint with the Twins this season. He had 24 appearances at Rochester, where he had a 3.34 ERA and four saves.
Waldrop started the season on the DL with a right elbow strain. He made four appearances for Minnesota between June 29 and July 7 before being sent to the minors.