Nick Franklin homered and drove in three runs for the Mariners, including an RBI in the eighth in which Oakland hurlers served up two wild pitches.
The uprising overcame a 4-2 Oakland lead and evened Seattle's record on its current road trip to 4-4.
Oakland outhit their guests 11-7, but the Mariners held the A's to one run on nine chances with runners in scoring position.
Brandon Maurer (4-7) stranded two Oakland runners in the seventh to pick up the win. Danny Fraquhar crafted a perfect ninth for his eighth save.
Sean Doolittle (4-5) took the loss in relief and also blew a save. Josh Donaldson and Nate Freiman homered for the A's, who lost for the second time in their previous six games.