Hanigan agreed to a minor-league deal with the Giants on Sunday, Jon Heyman of FanRagSports.com reports.
Hanigan was released by the Indians on Monday, T.J. Zuppe of The Athletic Cleveland reports.
Hanigan logged just five at-bats since returning from the disabled list in early September.
Hanigan (groin) was activated from the 10-day disabled list Thursday, Patrick Saunders of The Denver Post reports.
Hanigan was placed on the 10-day disabled list with a right groin strain.
Hanigan (illness) is starting at catcher and hitting eighth Sunday against the Brewers.
Hanigan was scratched from the Rockies' Thursday lineup with a stomach bug, Thomas Harding of MLB.com reports.
Hanigan went 3-for-4 with a double, two RBI and two runs during Wednesday's win over San Diego.
Hanigan (back) is starting behind the dish and hitting eighth Sunday against the White Sox.
Hanigan was scratched from a scheduled start Friday against the White Sox due to upper back spasms, Nick Groke of The Denver Post reports.