The Rockies overcame a one-run deficit with a five-run fourth inning and prevented Cincinnati from gaining ground in the race for the National League Central title.
Cincinnati remained 3 1/2 games out of first place, which is now shared by Pittsburgh and St. Louis.
Helton's first three-run homer came in the big fourth inning and he hit another one in the seventh. Colorado took a 9-3 led into the ninth.
Starter Jorge De La Rosa (15-6) benefited from the Colorado attack to get the win, surrendering three runs on eight hits in six innings. Bronson Arroyo (13-10) was roughed up for six runs on nine hits in 3 1/3 to take the loss.