Johnson pitched six solid innings and gave up an unearned run on two hits. After the game, Nationals president Stan Kasten was in the first-floor hallway at Nationals Park when he spotted Johnson and congratulated the left-hander on the magic number.
"It's a great moment in baseball history. As you know, it's a rare feat. He has had an amazing and long career," Kasten said. "All baseball fans everywhere should appreciate the magnitude of the accomplishment. Anyone who is a 300-game winner is by definition a superb player and a clear Hall of Famer. You can't say much more than that."
The 300th victory is fitting for Johnson, who won his first big league game in an Expos uniform in 1988. The Expos ended up trading him to the Mariners a year later.
"It's kind of weird. I don't know if you call it fitting," manager Manny Acta said. "He probably is not relating anything to it because we are the Washington Nationals now. But I don't think it happens very often."
Reliever Kip Wells, who is on the disabled list because of a right adductor strain, was watching the historic event in the clubhouse, and he was impressed about how Johnson went about his business to win his 300th game.
"It's a testament to how long it takes to do something like that -- how consistent you have to be, lucky you have to be, healthy you have to be and how you have to adapt during the course of your career," Wells said. "He went from throwing 97-98 miles per hour right down the middle to throwing back-door sliders to 2-1 changeups. It's a credit to him to be able to adapt like he has. He was able to stay healthy long enough to endure and win 300 games."
Both Wells and reliever Julian Tavarez don't think they will see another 300-game winner in the near future.
"It's not going to be seen very much in the next 50 years or however long because of health and all the other intangibles that go along with it," Wells said.
Said Tavarez: "I don't think anybody else will reach 300 games because Pedro Martinez is not playing. Congratulations to Randy. He really worked hard. I'm really happy for him."
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.