Asked about a Wikipedia entry on Garber's page that said he lives with partner Rainer Andreesen in New York, he confirmed his relationship, reports digitalspy.co.uk.
"I don't really talk about it but everybody knows. Andreesen is going to be out here with me for the Screen Actors Guild Awards," Garber said.
The 63-year-old, who stars in the Golden Globe-winning drama "Argo", is not the only celebrity to recently come out to the public.
Actress Jodie Foster, who received the prestigious Cecil B. DeMille trophy at the 70th Golden Globe award ceremony, used the platform to speak about her sexuality.