Mike Zunino homered and drove in all of Seattle's runs.
Hernandez (7-1) became the seventh pitcher in Mariners history with seven victories before June 1. He won his fourth consecutive start with his most dominant performance of the season.
Zunino gave Hernandez the lead with a two-out, two-run single in the second inning. He led off the eighth with a home run against C.J. Wilson (6-4).