Paul Goldschmidt drove in three runs while Justin Upton hit a solo homer and scored twice for the Diamondbacks, who have won three straight and 12 of their last 13.
With the win, Arizona maintained its seven-game lead over San Francisco for first place in the NL West as the Giants beat the Padres on Monday.
Wade Miley (3-1) won his third straight start as he was touched for just two runs on six hits with three walks and six strikeouts over seven innings.
"He pitched good for us out there again," said Arizona manager Kirk Gibson. "He always seems to struggle early, but then he finishes strong and gives us a chance to win."
Troy Tulowitzki hit a three-run home run in the ninth to make the game close, but it wasn't enough to keep the Rockies from losing for a fifth time in their past seven games.
Esmil Rogers (6-5) dropped his fourth decision in his past five starts as he gave up six runs on eight hits with five walks and two strikeouts over 5 1/3 innings.
Arizona carried a seven-run lead into the ninth, but Colorado didn't go quietly. With two outs, Dexter Fowler hit his second home run of the game. Mark Ellis and Carlos Gonzalez then each drew walks before Tulowitzki drilled a pitch over the wall in center to make it a three-run contest.
The two sides exchanged homers in the first inning as Upton hit his 27th of the year while Fowler led off the home half with his third blast.
Ellis hit a solo homer in the third to give Colorado a 2-1 lead, but Blum hit a two-run single in the fourth that scored Goldschmidt and Aaron Hill for a 3-2 advantage.
A five-run sixth inning solidified the lead for the Diamondbacks. Blum led off the frame with his second homer of the year. Later in the frame with two on and Josh Roenicke on the mound, Willie Bloomquist scored one with a single to center. After a fielder's choice groundout from Gerardon Parra and a hit-by- pitch to Upton that loaded the bases, Goldschmidt hit a bases-clearing double that saw him tagged out trying to reach third, but not before making it an 8-2 game.
Miley helped his cause with an RBI fielder's choice in the seventh while Kouzmanoff drove home one in the eighth for Colorado.
Collin Cowgill's RBI single in the ninth extended the lead to 10-3.
"He's very deceptive and I though so too," Colorado outfielder Ryan Spilborghs said of Miley.
Hill moved his hitting streak to eight games while Bloomquist extended his to seven...Arizona has won 12 of the 16 games with Colorado this season.