Hernandez (4-3) blanked the Rangers until allowing Mitch Moreland's homer in the ninth. The Mariners ace finished by yielding six hits while walking two and raising his strikeout total to 68.
That tied the right-hander with Detroit's Justin Verlander for the American League lead.
Ichiro put Seattle ahead with an RBI triple in the first and made it 2-0 two innings later with a run-scoring single. A second run scored on the play when Texas outfielder Josh Hamilton threw wildly to third.
Jesus Montero added a pair of RBI as Seattle logged its fourth straight win in the opener of a three-game set at Safeco Field.
Yu Darvish (6-2) absorbed the loss, issuing six walks en route to four earned runs over four innings. The right-hander struck out five.