Colorado overcame an early three-run deficit to take two of three from the Reds.
Gonzalez hit a solo homer in the first, a three-run blast in the fourth that gave the Rockies the lead and added a two-run shot in the eighth.
Tulowitzki went 5-for-5, hitting a two-run homer in the third and a solo affair in the eighth. Todd Helton added a two-run blast for the Rockies in the seventh.
Jon Garland (4-6) coasted six innings to get the win despite giving up four runs in the opening inning. He settled down after that to surrender just four hits overall.
The Rockies mauled Pedro Villarreal (0-1), who was making his season debut for Cincinnati and only the second appearance of his career. Villarreal, called up from Class AAA Louisville to make the start, gave up six runs on 10 hits in 3 2/3 innings.