Erik Bedard and a handful of relievers shut the Dodgers out until the ninth inning, and the Seattle offense pounded out 20 hits in an 18-2 victory.
Their first victory of the spring included home runs by Mike Wilson, Matt Tuiasosopo and Mike Carp, who had five RBI.
"It was good to see Adrian Beltre and Erik Bedard back out there, and we swung the bats pretty aggressively," manager Don Wakamatsu said.
Beltre's first game of the spring included two hits and an RBI, and he felt fine after playing.
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He'll test himself with one more game - playing third base against the Giants - and then decide whether to play for in the World Baseball Classic.
Two games into the Cactus League schedule, the Mariners are now 1-0-1.