Giambi was released by the Oakland Athletics earlier this month after hitting just .193 with 11 home runs and 40 RBIs in 83 games. He reportedly will join Triple-A Colorado Springs to get at-bats and then report to the Rockies on Sept. 1 when rosters are expanded.
"Jason is 100 percent healthy and definitely plans to continue playing," his agent Arn Tellem said in an e-mail to The Associated Press when Giambi was released. "He is confident he'll be able to contribute to a team down the stretch."
Giambi had been on the disabled list since July 20 with a strained right quadriceps muscle when he was released by Oakland.
The 38-year-old first baseman and designated hitter had returned to Oakland this season after seven pressure-packed years with the New York Yankees, agreeing in January to a one-year contract that guaranteed him $5.25 million.
Information from The Associated Press was used in this report.