Stanton hit his 42nd homer of the season, tying a franchise record set by Gary Sheffield in 1996 and leading Miami to a 5-3 victory over Colorado on Sunday afternoon at Marlins Park.
"I really enjoyed watching (Sheffield) play as a kid - it's good company to be in," Stanton said. "It's not something I will fully appreciate until the year is over. But it's a cool thing to have under my belt, and I have time to get more."
The Marlins (56-60) swept the series from Colorado (65-52). It was Miami's first three-game sweep since July 7-9 at the San Francisco Giants, and its first home sweep since beating the Philadelphia Phillies in May.
Colorado still has a four-game lead in the battle for one of two NL wild-card spots, but the Rockies have lost five of their past six games.
To make matters worse for Colorado, third baseman Nolan Arenado, who leads the majors in RBIs, was hit on the left hand by a pitch from Marlins starter Vance Worley. Arenado left the game immediately, but X-rays were negative.
"It hurt real bad," Arenado said. "It got real tight. That was my concern -- how tight it was getting. Luckily, it's not broken, but it's swollen pretty good. It's hard to move my pinkie.
"I've gotten hit in the hand before, but it didn't feel like this. It was a two-seam fastball, up and in. I tried to get out of the way, but it hit me. Whenever you get hit in the hand, it scares you."
Arenado, a four-time Gold Glove winner and a three-time All-Star, said he was told by team doctors that a stint on the disabled list is not likely.
"It will take some time," Arenado said, "hopefully (just) a couple days."
Either way, it was a frustrating series for Arenado, who was ejected from Saturday's game after he was called out on a check swing.
Stanton, who leads the majors in homers, had a much better weekend. He became the sixth-fastest player to reach 250 homers, dating to 1913. Stanton also has hit nine homers in the past 10 games and 21 in the past 33.
"Big G (Stanton) is impressive," said Marlins manager Don Mattingly, a great hitter in his day.
Besides Stanton, the key for Miami on Sunday was the bullpen. Starter Vance Worley lasted just four-plus innings and got a no-decision. But reliever Javy Guerra (1-0) got out of a two-on, two-out jam created by Worley in the fifth. Guerra pitched two hitless and scoreless innings, earning his first major-league win since 2014.
Overall, Miami's bullpen pitched five scoreless innings. That includes Odrisamer Despaigne, who pitched a scoreless ninth to earn his first major-league save.
Colorado starter German Marquez (9-5) took the loss, allowing five runs in 4 1/3 innings. His streak of six straight quality starts -- a Rockies rookie record -- was snapped. He had been 4-0 with a 2.95 ERA during that stretch.
Miami opened the scoring with two runs in the second. After J.T. Realmuto was hit by a pitch and Tomas Telis singled, the Marlins had runners on second and third with two outs.
On a 2-2 count, Worley hit an outside pitch to right field. Colorado's Carlos Gonzalez made a diving catch, but it was trapped, and his strong throw home could not prevent two runs from scoring.
Colorado took a 3-2 lead in the third. Like Miami's rally, this one was also started by a leadoff hit-by-pitch. After Charlie Blackmon was plunked and DJ LeMahieu singled, Colorado pounced.
Gerardo Parra had an RBI single, and Gonzalez hit a two-run single. Ryan McMahon nearly had an RBI groundout. But upon video replay, he was called out at first, and the Marlins took a run off the board on an inning-ending double play.
Stanton's homer, an opposite-field job to right in the bottom of the third, tied the score 3-3.
"It was a good pitch," Marquez said of his 98-mph fastball on the outside corner. "But he's a good hitter."
Miami took a 5-3 lead in the fourth on Mike Aviles' two-round double into the left-field corner, and the bullpen did the rest.
NOTES: Rockies rookie 1B Ryan McMahon, who made his first big-league start, got an eighth-inning single for his first hit. ... Marlins RF Giancarlo Stanton leads the majors with 19 go-ahead homers, which is also a franchise record. Stanton's homer on Saturday was No. 100 for him in his career at Marlins Park. ... Rockies manager Bud Black (illness) was back in the dugout after missing Saturday's game. ... The Rockies return home on Monday to face the Atlanta Braves. Colorado RHP Chad Bettis, who was diagnosed with testicular cancer in November of 2016, will make his 2017 big-league debut. ... The Marlins on Monday open a three-game series against the visiting San Francisco Giants.