The Phillies selected Stevenson's contract from Triple-A Lehigh Valley on Friday.
The 27-year-old was claimed off waivers from the Giants in late May but was designated for assignment before receiving a look in the big leagues. Stevenson has spent the past two months at Lehigh Valley, where he has a .304/.419/.484 slash line with seven homers and 27 steals in 90 games. He'll provide outfield depth as Austin Hays (hamstring) heads to the injured list.