Hernandez scattered five hits, striking out nine and walking one as he reached a century of wins at the fourth attempt.
Kyle Seager, Jesus Montero and Kendrys Morales all homered for the Mariners.
Mike Napoli hit a grand slam as the Boston Red Sox eased to a 9-6 win over the Oakland Athletics.
Napoli also had an RBI double as he drove in five in total, while Will Middlebrooks busted out of a slump with a three-run homer.
The Cincinnati Reds scored three times in the bottom of the 13th to snatch an unlikely 5-4 win over the Chicago Cubs.
The Cubs appeared set for victory when Luis Valbuena launched a two-run shot in the top of the 13th, but the Reds pulled level on a two-run double from Jay Bruce, then walked off when Cesar Izturis drove in Bruce.
Ryan Braun and Yuniesky Betancourt each homered and drove in three as the Milwaukee Brewers overcame the San Diego Padres 7-1.
Ryan Roberts homered twice as the Tamba Bay Rays beat the New York Yankees 5-1, while AJ Pierzynski went yard in the ninth to drive in the go-ahead run and give the Texas Rangers a 7-6 victory over the Los Angeles Angels.
Jonathan Pettibone struck out six on his MLB debut as the Philadelphia Phillies beat the Pittsburgh Pirates 3-2, while the St Louis Cardinals overcame the Washington Nationals by the same scoreline.
The Baltimore Orioles beat the Toronto Blue Jays 2-1, the Cleveland Indians were 3-2 winners over the Chicago White Sox and the San Francisco Giants edged out the Arizona Diamondbacks 5-4.