Yunel Escobar drew a lead-off walk from Joe Savery (0-2), went to second on a balk and to third on Mike McCoy's groundout.
After J.P. Arencibia fanned for the second out, Davis lashed a ground-rule double to center field, handing Toronto a victory and clinching its three-game interleague series.
Francisco Cordero (2-4) earned the victory with a scoreless top of the 10th.
Arencibia's RBI double capped a three-run eighth inning that saw the Blue Jays erase a 5-2 deficit.
Escobar finished 3-for-4 with solo homer while Davis and Colby Rasmus each added two hits and an RBI in the victory, which put the Blue Jays over .500 at 33-32.
John Mayberry slammed a three-run homer for the Phils, who dropped to 4-11 in June.