"Finally," he said with a huge grin. "It took too long."
Hernandez pitched six scoreless innings and Seattle homered three times to back him up in a 7-1 victory over the Astros.
"Tonight I was like: 'You've got to do it (Monday). You can't wait more and more time. You've just got to go out there and have a good game,'" he said.
Hernandez (2-2) joins Jamie Moyer (145) and Randy Johnson (130) as the only pitchers to reach 100 wins with the Mariners.
He didn't realize that there were only two other players to reach the mark with Seattle and said he was honored to be on the exclusive list.
"It's a great accomplishment," Seattle manager Eric Wedge said. "I'm really happy for him that he was able to accomplish that at such a young age. He's accomplished so much so quickly for a young man."
Hernandez allowed five hits and struck out nine to lower his ERA to 2.08. He came in with the second-lowest run support in the AL at 1.88, and didn't factor into the decision in his last start despite striking out 12 and allowing no earned runs in eight innings.
He had no such trouble Monday night as Seattle took a 1-0 lead in the first and tacked on two runs in each of the third, fourth and fifth innings.
Kyle Seager, Jesus Montero and Kendrys Morales all homered for the Mariners, who snapped a three-game losing streak.
"It was a great day offensively and even better to get Felix some runs early so he could settle in and do what he does," Seager said.
Hernandez, who threw the only perfect game in Mariners history last August, struggled to rank this moment among the many things he's already done at just 27.
"I might think about it in my room," he said. "I've got 100 and I just feel so happy right now."
Rick Ankiel hit a solo homer in the seventh inning for the Astros, who dropped to 5-14 - the second-worst start in franchise history, according to STATS. They opened 4-20 in 1969.
"It's tough," Houston's Carlos Pena said of the losses. "We take pride in what we do, and every time we lose it eats away a little piece of us - there's no doubt about that."
Houston starter Brad Peacock (1-2) yielded nine hits and seven runs - both season highs - in 4 1-3 innings. The Astros' pitching staff has allowed 10 home runs in the last three games.
"When you don't pitch well you put yourself in a hole against a guy of (Hernandez's) caliber, fighting an uphill battle," Houston manager Bo Porter said.
Monday was just the third time the Mariners had ever visited Houston and their first trip since June 2007. They'll make three visits this year alone with Houston's move to the AL-West.
Seattle's hitters bounced back from a tough weekend where they went 1 for 24 with runners in scoring position and were shut out twice in a three-game sweep by the Rangers.
They got things going early in this one when Seager extended his hitting streak to a career-best 11 games with a single with one out in the first. Morales walked before Seager advanced to third on a passed ball by Castro with two outs.
Justin Smoak sent Seager home with a groundball single that glanced off first baseman Pena's glove and into the outfield to make it 1-0.
Seager put the Mariners up 3-0 in the third when he launched a two-run homer to the second deck in right field. He has scored six runs and drove in eight during his hitting streak.
Montero added a two-run shot to center field in the fourth to push the lead to 5-0.
Morales led off the fifth inning with a home run to right field to make it 6-0. Smoak doubled and scored on a sacrifice fly by Montero later in the inning.
The Astros couldn't string any hits together against Hernandez. The only time they had more than one baserunner against him was in the fourth, but thanks to a baserunning gaffe that didn't last long.
Jason Castro walked with no outs in that inning before Chris Carter broke a 0-for-16 slump with a bloop single to shallow center field. Castro thought the ball was caught and sprinted back to first base, leaving both he and Carter there.
The umpires discussed the play for a couple of minutes before ruling that Carter was out for passing a runner on the basepath.
Center fielder Franklin Gutierrez was injured trying to make the catch and left the game with tightness in his right hamstring. Wedge said that he could be headed for the disabled list, but that they'd know more about the injury on Tuesday.
Houston reliever Jose Cisnero made his major league debut when he replaced Peacock in the fifth inning. He was a bright spot for the Astros, allowing two hits in 3 2-3 scoreless innings.
NOTES: Seattle's Michael Morse went 0 for 5 to break a nine-game hitting streak in Houston. ... The series continues on Tuesday when Houston's Bud Norris opposes Hisashi Iwakuma. ... The Astros recalled Cisnero from Triple-A Oklahoma City and optioned LHP Brett Oberholtzer there before the game. ... Houston Rockets players Chandler Parsons and Aaron Brooks attended the game a night after losing to Oklahoma City in the first game of their first-round playoff series with the Thunder.