The Mariners erupted for five runs in the second to take control of the game and log a victory in the first of a three-game series against the Athletics.
Casper Wells and Chone Figgins delivered one-out singles and Franklin Gutierrez broke a scoreless tie with a double. After Ichiro Suzuki reached on a fielder's choice, Brendan Ryan made it 2-0 with a single to shallow left.
That's when Ackley delivered the big blow, lining a pitch to right field that skipped past Ryan Sweeney and rolled all the way to the wall, driving in three runs.
Blake Beavan (2-2) got the win in a 6 2/3-inning start during which he gave up three runs on seven hits, walking two and fanning three.
Oakland's Trevor Cahill (9-10) was pounded for 12 hits over four innings, allowing seven runs.
Kurt Suzuki drove in runs with an RBI double and solo homer for the A's.