Oakland won for just the second time in eight games, a struggling stretch that has followed four straight wins.
Jed Lowrie hit a three-run blast in the Oakland first and Yoenis Cespedes followed with a solo shot later in the inning. The Athletics built a 6-3 lead through two innings before Reddick began his assault.
Reddick hit solo homers in both the third and fifth innings before unloading with a three-run shot in the sixth.
Oakland pounded out 17 hits to make things easy for Jarrod Parker (8-6), who picked up the win by limiting Toronto to three runs on six hits in six innings.
Exploding whale video goes viral on Internet
Man spent 15 hours in jail for plugging electric car into an outlet at a school