Trevor Story also had two hits, including a triple, and added two stolen bases. The Rockies have won two straight games after dropping the previous seven and have pushed back to .500 with a 15-15 record.
''Hopefully I continue to have good at-bats, continue to be ready to hit,'' Arenado said. ''It was nice to drive in runs and help the team win.''
Daniel Bard gave up a run in the ninth but still earned his second save in two nights. The Diamondbacks loaded the bases with two outs but Nick Ahmed struck out to end the game.
''A lot of time it's not easy in the ninth. The ninth is a different animal,'' Colorado manager Bud Black said. ''But Daniel worked through it and made some pitches.''
Arizona lost its seventh straight and fell to 13-18.
The Rockies' decisive rally came in the seventh. Story drew a one-out walk and stole second before coming home on Arenado's second double of the night. Later in the inning, Arenado scored on a passed ball to push the Rockies ahead 5-3.
Arenado, a five-time All-Star and seven-time Gold Glove third baseman, has struggled some by his lofty standards and came into the game batting just .223. He was just 5 of 37 at the plate over his previous 10 games.
''I think Nolan's getting closer. A couple good swings,'' Black said.
Colorado took a 2-0 lead in the first with three extra-base hits. Story started the action with a long triple into the right-center gap and Arenado brought him home with a double. Two batters later, Matt Kemp followed with another double that scored Arenado.
The D-backs bounced back to tie it at 2-all in the second thanks to solo homers from Christian Walker and veteran Jon Jay. It was the first homer in more than two years for Jay, who went 108 games and 384 plate appearances between long balls.
Arizona had just one hit in 14 at-bats with runners in scoring position.
''Nobody's going to feel sorry for us. We've got to find our way out of this now,'' Arizona manager Torey Lovullo said. ''That's what we love about this game. We're up and down junkies. We learn to deal with those things.''
Jairo Diaz (1-1) earned the win by pitching a scoreless sixth inning. Stefan Crichton (2-1) took the loss after giving up two runs in the seventh.
Colorado had a strange first half to the season. The Rockies started out as one of the hottest teams in baseball with a 11-3 record but regressed over the next few weeks.
Now they're halfway through the abbreviated schedule. Arenado said everyone's adjusting to the compressed timetable.
''It feels like we just started and now we're almost done,'' Arenado said. ''That's the disappointing part about playing a 60-game season, but at the same time, it's better than nothing. We're happy to be back out here, battling and trying to get back to that playoff.''
Arenado's cousin Josh Fuentes got his first start of the season at first base. He had two hits, including a double.
Rockies: Catcher Tony Wolters didn't start one day after taking a foul ball off his left knee in the ninth inning. Drew Butera started but Wolters entered the game in the sixth after Daniel Murphy pinch hit for Butera.
Diamondbacks: Arizona is down two starting pitchers with both Madison Bumgarner and Merrill Kelly on the injured list. Bumgarner could return soon. Manager Torey Lovullo said the veteran left-hander will have a bullpen session on Wednesday and then the team will determine if he's ready to re-join the rotation. ... Lovullo said RHP Merrill Kelly had a small blood clot in his right throwing shoulder and had a procedure to have it dissolved. Kelly was scratched from Monday's start because of shoulder discomfort and went on the 10-day injured list.
Rockies: RHP Jon Gray (1-3, 6.23) will take the mound on Wednesday. He's given up 15 earned runs over his past 14 innings.
Diamondbacks: LHP Robbie Ray (1-3, 8.33) will try to shake a rough start to the season. The hard-throwing veteran has struggled with his command, walking 25 batters in 27 innings.
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