The Brewers received $1 in return, according to general manager Doug Melvin, who proposed the deal after the Braves lost All-Star catcher Brian McCann to a rib-cage injury on Tuesday night. Atlanta also must take-on what remains of Nieves' $775,000 salary.
Maldonado was hitting .265 with 39 RBIs in 78 games for Nashville and Double-A Huntsville this season. He's considered an outstanding defensive catcher.
Nieves was the Brewers' Opening Day catcher because regular starter Jonathan Lucroy began the season on the disabled list with a fractured finger. Nieves had two hits in that game, then went 5-for-46 (.109) and slugged .130 before the Brewers sent him outright to Nashville.
He had not fared much better in the Minors, batting .170 (15-for-88) through Tuesday.