The 29-year-old right-hander spent the last four seasons with Pittsburgh but then became a free agent when the Pirates declined to offer him a contract by the Dec. 20 deadline. He was 6-11 with a 5.05 ERA in 28 starts and six relief appearances last year. He has a 39-42 career record with a 4.74 ERA.
If he is on Colorado's Opening Day roster, his salary would be increased to $850,000. He would also have the chance to earn $300,000 in performance bonuses.
Fogg said Washington, San Francisco and Cincinnati also pursued him before he decided to sign with the Rockies.
"I think it's an organization on the way," Fogg said. "They've got a lot of guys who buy into the same aspect of playing hard and trying to win baseball games."
Fogg is 1-1 with a 5.25 ERA in two starts at Coors Field, according to the Elias Sports Bureau.
"I've pitched there a few times already in my career and had some decent success," he said. "Denver is a great city."
Also Thursday, the Rockies released 26-year-old right-hander Ryan Speier and re-signed him to a minor-league contract. Speier had shoulder surgery on Feb. 1 and will likely miss the season.
He went 2-1 with a 3.65 ERA in 22 relief appearances last year.