Sorry, girls ... Joey Fatone is officially off the market.

The 'NSYNC member announced Tuesday night that after 10 years of dating -- and having a child together -- he has asked his girlfriend to marry him.

Fatone told CBS' "Late Late Show" host Craig Kilborn that he popped the question to longtime girlfriend Kelly Baldwin on June 18 in Orlando, Florida. "It was exciting, it was fun," Fatone said.

He said Baldwin had always wanted to be proposed to at the Palace of Fine Arts in San Francisco, where she had never been, so he brought the 88-year-old Greco-Roman structure to her, in the form of a billboard about 56 feet wide and 20 feet tall that he set up in front of his house. He commissioned the billboard through "a friend of mine that works in an ad agency that does the billboards in Times Square, like, the really big billboards," he said.

"So when I drove up, I said, 'What's the one place that I didn't take you?' So we drove up, she saw the Palace of Fine Arts [billboard], I went on my knees, got all teary-eyed, and I just froze for a second. So I was like, 'Hey, will you marry me?' "

Baldwin is the mother of Fatone's 2-year-old daughter, Brianna. A wedding date has not yet been announced.