On Thursday, Cleveland traded Mills to Cincinnati in exchange for cash in a Minor League deal. Mills has been assigned to Double-A Pensacola in the Reds' organization after spending the beginning of the season with Triple-A Columbus.
The Tribe made Mills the 13th overall selection in the first round of the 2007 First-Year Player Draft.
In parts of six Minor League seasons with Cleveland, the 25-year-old Mills hit .267 with a .330 on-base percentage and a .444 slugging percentage. The left-handed hitter piled up 76 home runs and 375 RBIs in 569 professional games for Indians affiliates.
This season, Mills hit just .197 with a .239 on-base percentage to go along with seven homers and 21 RBIs in 39 games for Triple-A Columbus. Mills was third on the depth chart behind Matt LaPorta and Russ Canzler at first base for the Clippers. Mills also spent some time as a designated hitter and has limited experience as a third baseman.