Hernandez (13-5) improved to 9-0 with a 1.40 ERA in his last 14 starts with the dominating performance against Minnesota, during which he twice stranded runners on third base.
The Mariners ace issued one walk and struck out five in the 100-pitch gem as Seattle took the opener of a four-game series.
Eric Thames socked a solo homer in the eighth inning to provide the contest's only offense.
Liam Hendricks (0-7) absorbed the hard-luck loss for Minnesota, surrendering just the Thames shot in a complete-game effort. The Australian right-hander yielded only three hits, walked three and struck out six.