Hernandez retired 12 of the last 13 batters he faced, leading Seattle to a 9-5 victory over the Chicago White Sox.
"I'm definitely ready," he said.
The right-hander allowed two runs and three hits, struck out five and walked none while throwing 79 pitches.
The Mariners scored four runs in the sixth to take a 7-3 lead, helped by a two-base error on Chicago first baseman Adam Dunn. Mike Wilson had a run-scoring double and Matt Tuiasosopo added a two-run double.
Chicago committed four errors in the game.
Chone Figgins also had a two-out, two-run single for Seattle in the fourth.
White Sox starter Edwin Jackson walked five in five innings. He gave up three runs and six hits, and struck out six.
"He had some problems with command," Chicago manager Ozzie Guillen said. "But I'm happy with where he is."
"The second inning was a little rough," Hernandez said. "I was getting behind in the count but after that I quit thinking about everything and just threw the ball down in the strike zone."
Brendan Ryan, announced as the Mariners' opening-day shortstop before the game, made the day's best defensive play. He scooped up a grounder that caromed off third baseman Josh Wilson and fired to first for an out in the fifth inning.
Mariners C Miguel Olivo will catch three innings in a minor league intrasquad game Wednesday. Olivo is coming back from a groin injury and hasn't played in a spring game since March 5. ... The White Sox optioned OF Alejandro De Aza, C Tyler Flowers and RHP Gregory Infante to Triple-A Charlotte and reassigned RHP Brian Bruney, OF Jordan Danks, RHP Jeff Gray, RHP Josh Kinney, RHP Shane Lindsay and INF Dallas McPherson to minor league camp. ... White Sox RHP Jake Peavy (right shoulder pain) played catch for five minutes at distance of 30 feet.