Bass, who formed *NSYNC with Justin Timberlake, JC Chasez, Joey Fatone and Chris Kirkpatrick, tells People magazine that he didn't earlier disclose his sexuality because he didn't want to affect the group's popularity.
"I knew that I was in this popular band and I had four other guys' careers in my hand, and I knew that if I ever acted on it or even said (that I was gay), it would overpower everything," he tells the magazine.
*NSYNC is known for a string of hits including "Bye Bye Bye" and "It's Gonna Be Me." The band went on hiatus in 2002. Bass has also found headlines for undertaking astronaut training and failing to raise money for a trip into space.
Bass says he wondered if his coming out could prompt "the end of *NSYNC." He explains, "So I had that weight on me of like, 'Wow, if I ever let anyone know, it's bad.' So I just never did."
The singer says he's in a "very stable" relationship with 32-year-old actor Reichen Lehmkuhl, winner of season four of CBS' "Amazing Race."
Bass and Fatone, 29, are developing a sitcom pilot inspired by the screwball comedy "The Odd Couple," in which his character will be gay.
"The thing is, I'm not ashamed -- that's the one thing I went to say," Bass says. "I don't think it's wrong, I'm not devastated going through this. I'm more liberated and happy than I've been my whole life. I'm just happy."