The Twins made the move Wednesday. They also moved left-hander Ron Mahay from the 15-day disabled list to the 60-day DL to make room for Flores on the 40-man roster. Mahay injured his right shoulder last weekend when he stumbled off the mound to field a grounder.
Mahay's injury left the Twins with just one healthy lefty in the bullpen in middle man Glen Perkins.
Manager Ron Gardenhire said Flores was flying to Texas and would be available in the bullpen Thursday night for the series finale against the Rangers.
Flores is 2-0 with a 2.96 ERA in 27 1/3 innings for the Rockies this season. Opponents are hitting just .224 off of him, but he has allowed 22 hits and 13 walks in 47 appearances.
"He knows what he's doing," Gardenhire said. "He has a track record."
The Twins planned to make a roster move after their game Wednesday night to open a spot on their active roster for Flores.
Flores has appeared in 339 major league games since 2002 for Texas, Colorado and St. Louis. He has a career 4.60 ERA.