The actor who appears as Spock in the new Star Trek movies and who also starred in TV's Heroes, made the revelation in a new interview about his work on Broadway.
Quinto, 34, won raves in Angels in America, a revival of the Pulitizer Prize-winning play set in the early days of the AIDS epidemic.
PHOTOS: Stars Who Have Come Out As Gay
It was “the most challenging thing I’ve ever done as an actor and the most rewarding” he told New York magazine.
"And at the same time, as a gay man, it made me feel like there’s still so much work to be done, and there’s still so many things that need to be looked at and addressed.”
PHOTOS: Hollywood’s Gay & Bisexual Community
Quinto has played numerous gay roles in the past and has been active in gay causes but he's never previously addressed his own sexual orientation.
He played a gay character on Tori Spelling’s TV show So NoTORIous, and another on the new F/X series, American Horror Story.
PHOTOS: Celebrity Smooches
In the interview, Quinto took a look at the growing number of states where gay marriage is now legal while at the same time gay teens are being bullied to the point of committing suicide.
"As a gay man I look at that and say there’s a hopelessness that surrounds it, but as a human being I look at it and say ‘Why? Where’s this disparity coming from, and why can’t we as a culture and society dig deeper to examine that?’ We’re terrified of facing ourselves.”
Quinto's next movie is the financial thriller Margin Call, opening Friday.
