The 33-year-old has previously discussed an incident where she was abused by an industry figure in general terms.
Lily said the man put her to bed to sleep it off after getting "smashed" at a party.
Speaking to the Guardian Weekend magazine, the LDN singer alleged: 'I woke up at 5am because I could feel someone next to me pressing their naked body against my back.
She then detailed the alleged assault further, stating: "I was naked, too".
'I could feel someone trying to put their penis inside my vagina and slapping my arse as if I were a stripper in a club.
Allen said she "moved away as quickly as possible and jumped out of the bed, full of alarm. and ran out of his room". She expresses her frustration that she did not confront or report the man's behaviour, and carried on working with him, explaining that she felt silenced because he had more power and money than her, and that she feared being labelled "hysterical" and a "difficult woman". "I wanted it on record that I'd been sexually abused by someone I worked with". The interview claims she wanted to name the executive in the book, but did not after being advised by her publisher.
According to Allen, music industry insiders have largely ignored the #MeToo movement, resulting in "a potent mix of sex, youth and availability" that has affected many singers and their careers.
"I expected him not to take advantage of my weakness", she writes. "I just couldn't tell them why I couldn't take the slot", she says.
Lily Allen has been sharing details of the sexual abuse she suffered at the hands of record company men. Turning the gig down, she says, caused Radio 1 to punish her by refusing to play her single "Trigger Bang". "It was consensual, sure".