The 30-year-old Kouzmanoff has been at Triple-A Sacramento since being demoted on June 6 to make room for Scott Sizemore. The A's announced the move Tuesday.
Oakland also purchased the contract of catcher Anthony Recker from Sacramento. Catcher Landon Powell was optioned to Sacramento on Monday. To make room on the 40-man roster for Recker, the A's transferred right-hander Trystan Magnuson to the 60-day DL because of right shoulder tendinitis.
Kouzmanoff was in his second year with Oakland. He began the season as the starting third baseman but was hitting only .221 with four homers and 17 RBI in 46 games when he was sent down.