Jed Lowrie went 3-for-4 with an RBI single for Oakland, which snapped a five-game losing streak.
Jarrod Parker (2-5) notched the decision, surrendering three runs on three hits over 6 1/3 innings. The right-hander overcame four walks and struck out five.
Sean Doolittle and Ryan Cook combined for 1 2/3 scoreless relief frames and Grant Balfour notched his sixth save despite allowing a pair of runners in the ninth.
Seattle's Brandon Maurer (2-5) was the loser, yielding three runs on six hits in five innings.
Kelly Shoppach belted a two-run homer for the Mariners.