Kevin Kouzmanoff had three hits and two 3, in the final regular season game for both teams.
Drew Pomeranz (2-1) tossed 5 2/3 innings of three-run ball to pick up the win. Acquired from the Indians in the Ubaldo Jimenez deal, Pomeranz scattered six hits while fanning three for the Rockies, who finished the regular season at 73-89.
"We're going to get busy here a hell of a lot sooner than later and work on some of the things that are necessary to turn the tables on what is definitely a disappointing season," Rockies manager Jim Tracy said of the 2011 season.
Giants rookie Eric Surkamp (2-2) was roughed up for four runs in 4 2/3 innings. He allowed eight hits while striking out three and walking two.
Mark DeRosa had two hits and knocked in two runs for the Giants.
The defending World Series Champions ended the year 86-76.
"The fact that we were able to be in it at the end with the injuries that we had, the ball not bouncing our way, those hits that didn't seem to fall for us. We learned a lot about the caliber of men that I was playing alongside with," Giants pitcher Sergio Romo said of the 2011 campaign.
Eric Young led off the game with a stand-up triple, as he sliced a fly ball off the right field wall. He scored on Dexter Fowler's line drive single up the middle. Seth Smith brought Fowler home with an RBI groundout.
The Rockies tacked on two more runs in the fifth on a pair of RBI singles by Kouzmanoff and Pacheco.
San Francisco made it a 4-3 game with three runs in the sixth. Jeff Keppinger singled to center to score Justin Christain, who doubled to left to start the frame. DeRosa plated two with a single to center.
Colorado added two more runs in the seventh on a Kouzmanoff RBI double to right-center field, and a Pacheco run-scoring single.
Rafael Betancourt came on in the ninth to earn his eighth save of the season.
The Rockies improved to 25-23 against left-handed starters this year, but went 48-66 against right-handed starters...Colorado finishes its season 35-46 on the road, while San Francisco finishes its year 46-35 at home.