Dominguez homered twice and had four RBIs, helping the Astros to defeat the Chicago White Sox 8-2.
Dominguez hit his sixth and seventh homers of the season off White Sox lefty John Danks (3-4) in the third and fifth innings.
The first was hit to deep left-center on a full count that followed a double by Dexter Fowler. The second was hit to the left-field Crawford Boxes, also with Fowler on base, putting the Astros up 8-1.
"He's a guy that can turn around anybody's fastball," Astros manager Bo Porter said of Dominguez. "He's got power to all fields."
Backed by early run support, Astros right-hander Brad Peacock (1-4) earned his first win of the season, allowing two runs and five hits and four walks, while striking out five in 6 2/3 innings.
The Astros scored two runs or fewer in six of Peacock's previous nine outings entering Sunday.
Since Peacock became a starter on April 20, the offense provided 13 runs of support in his previous five starts.
"Our hitters came out swinging," Peacock said. "It's a big confidence builder for them and a big confidence builder for us."
The Astros have won four of their past five games, while the White Sox have lost six of eight. After taking two of three from the Rangers and White Sox, Houston has won back-to-back series for the first time since last August.
The Astros improved to 12-3 when hitting two or more home runs. They are 1-17 when they fail to hit a homer.
After a Chris Carter homer in the second inning gave the Astros an early lead, Jonathan Villar sparked a rally with a two-RBI single that scored Jesus Guzman and L.J. Hoes. Guzman advanced to second on a throwing error by left fielder Alejandro De Aza then stole third and scored when catcher Adrian Nieto's attempt to throw him out skipped into the outfield.
The Astros had 10 hits in the game and have had at least nine hits in eight straight games, the club's longest such streak since 2008.
"They were swinging it good," White Sox manager Robin Ventura said. "Any time you get the ball up, especially in this ballpark, you're going to create a lot of problems."
Villar later left the game in the seventh inning with a right hand injury, but Porter said the injury was not serious.
The White Sox were playing without first baseman Jose Abreu, who was placed on the 15-day disabled list Sunday with ankle tendinitis.
"Everything gets frustrating, especially when you have games like this," Ventura said of Chicago's two errors. "It just needs to be cleaned up."
Danks allowed eight runs -- seven earned -- and 10 hits and three walks while striking out seven in 4 2/3 innings. He allowed at least one homer for his fourth consecutive start and fell to 1/3 in that stretch after allowing just one homer through five starts in April, when he was 2-1.
"I did a terrible job of keeping the ball in the ballpark," Danks said.
Despite having the worst record in the AL at 16-28, the Astros are 15-11 when hitting home runs. The Astros rank third in the majors and second in the AL with 15 multi-homer games. ... Dexter Fowler has walked in eight straight games, Houston's longest streak since 2006. ... Astros prospect C Brian Holberton hit for the cycle at Class A Quad Cities, going 5 for 5 with two singles, a double, triple, two-run homer and five RBIs in a 10-3 win. ... The Astros begin a 10-game road trip to Anaheim, Seattle and Kansas City, and the White Sox travel to Kansas City for a three-game series.