De La Rosa (6-3) continued a recent hot streak, reeling off his fourth victory in four starts. The left-hander held the Diamondbacks to one run on six hits while walking two and striking out five.
Gonzalez put the Rockies ahead to stay with a first-inning homer, then added an RBI triple and scored on a wild pitch in the third for a 4-0 Colorado lead.
Dexter Fowler went 2-for-4 with a run scored as the Rockies claimed the rubber match of their three-game series with division rival Arizona.
D-backs starter Trevor Cahill (3-5) yielded four runs on seven hits over six full frames.
Wil Nieves supplied Arizona's only RBI.