Gonzalez, 29, went 3-1 with a 5.04 ERA in six starts for the Astros last season after having his contract purchased from Triple-A Oklahoma City on Sept. 3. He has pitched in parts of nine Major League seasons with Arizona (2003-08), Oakland ('09), Colorado ('11) and Houston ('12).
Gonzalez is expected to compete for a spot in the back end of the Astros' rotation. His contract calls for him to make $525,000 if he's on the Major League roster and includes incentives for games pitched.
Valdez, 29, compiled a 2.25 ERA in 12 relief appearances after being a September callup for the Astros last season. He spent the majority of his season with Oklahoma City, where he posted a 4.95 ERA with 21 saves in 46 relief appearances.
Valdez will make $500,000 if he's on the Major League roster, and he has the option of signing with a Japanese club.