"College wasn't the only learning experience I undertook during my years in New York," UsMagazine.com quoted the Brooklyn College graduate as writing in his book. "I was also coming to terms with my sexual identity. Since I was knee-high to a duck, I've known that I was gay."
Set for release June 16, the book is dedicated to Tyler Clementi, the Rutgers University student who committed suicide last September after being taunted by classmates about his sexuality, UsMagazine.com said.
Lemon said in his book he told his mother about his sexual orientation, but "still chose to keep those secrets hidden from the world."
"I, like most gay people, lived a life of fear," he said. "Fear that if some employers, co-workers, friends, neighbors and family members learned of my sexuality, I would be shunned, mocked and ostracized. It is a burden that millions of people carry with them every single day."