HOUSTON -- Houston Astros designated hitter Carlos Beltran, signed as a free agent last offseason for moments like these, surveyed the raucous scene in the home clubhouse at Minute Maid Park equally joyous and appreciative, experienced enough to know how to embrace the present.

Right-hander Justin Verlander delivered a third consecutive strong start for the Astros, who bashed four home runs in support in their 7-1 win over the Seattle Mariners on Sunday, a victory that secured their first American League West pennant in franchise history.

Houston won its first division title since 2001 when it claimed the National League Central. This marks the Astros' seventh division crown overall and 11th postseason appearance in franchise history. It's the second playoff berth in three seasons with manager A.J. Hinch.

As for Beltran, who made six postseason appearances with five different teams, including the Astros in 2004, he recognizes the significance of celebrating the accomplishment of a division title fully and with the gratitude of comprehending just how fleeting these moments can be.

"The guys are really embracing and understanding that when you win a series it's a big deal. That's how you're capable of winning divisions," said Beltran, a 20-year veteran. "We're excited, we're happy and we're looking to playing good baseball in October."

Verlander (13-8) allowed one run on three hits and one walk with 10 strikeouts over seven innings. In three starts with the Astros (91-58) since his acquisition from the Detroit Tigers at the waiver trade deadline, Verlander is 3-0 with an 0.86 ERA and 26 strikeouts over 21 innings.

Derek Fisher and Marwin Gonzalez belted two-run home runs in the fifth inning to help the Astros erase a 1-0 deficit. Fisher socked his fifth home run off Mariners right-hander Andrew Moore (1-4); Gonzalez greeted Seattle reliever James Pazos with his 22nd homer on the season.

"Just a couple mistakes that can come back to bite you," said Moore, who allowed three runs on seven hits with one strikeout over 4 2/3 innings. "Facing a good lineup like that, they take advantage of bad pitches. That's what Fisher did."

The Astros began the celebration in earnest in the seventh inning when George Springer lofted his team-leading 32nd home run into the first row of seats of the Crawford Boxes in left field. Two batters later, Carlos Correa blasted his 21st dinger to straightaway center field, a 420-foot two-run blast. Both of those home runs came against Mariners right-hander Emilio Pagan.

Houston remains in contention for the best record in the AL, trailing the Cleveland Indians by one game in the loss column in pursuit of homefield advantage in the postseason. The Astros have enjoyed a steady ascension after posting three consecutive 100-loss seasons between 2011-13, producing a 19-win improvement in 2014 before earning a wild-card berth in 2015.

"From being in 2013 back when the organization had some ups and downs, to come this far is something special," said Springer, who debuted April 16, 2014. "I'm happy to be a part of it."

The Mariners (74-76) grabbed a 1-0 lead against Verlander when left fielder Ben Gamel belted his 10th home run into the home bullpen with one out in the third inning. But Verlander proved too overwhelming as did the Astros, who claimed the season series against the Mariners 14-5.

Houston moved into sole possession of first place in the AL West on April 14 with a 7-2 win over the Athletics. Six weeks later, their lead was 10 games, and the Astros never looked back.

"We did a lot right this year to get to this point," Hinch said. "It's been a long journey. I know we made it look easy sometimes; the players are really good. But it's not easy going wire-to-wire the way we did."

NOTES: With Astros RHP Lance McCullers deemed unfit to start on Tuesday, RHP Collin McHugh will get the nod against the White Sox. McCullers will continue to throw bullpen sessions until his arm fatigue is no longer an issue. ... When Mariners LF Ben Gamel smacked a solo home run in the third inning, he became the eighth Seattle player to reach double digits in homers. This marks the seventh time in club history that the Mariners have had at least eight players hit 10 homers in a season. ... With his strikeout of Gamel to cap the fifth inning, Astros RHP Justin Verlander reached 200 strikeouts in a season for the seventh time in his career.