In an interview set to air on "60 Minutes" on Sunday, he revealed he was sexually abused by a camp counselor.
The Massachusetts Republican, who gained fame when he won late Sen. Edward M. Kennedy' seat, also said he was emotionally and physically abused at the hands of his stepfathers.
Brown said even those closest to him, his wife and his mother, had no idea of the abuse.
The senator said he hopes the childhood physical and sexual abuse he writes about in "Against All Odds" can inspire others to overcome similar challenges.
The book comes out on Monday.