Jeremy Frazer Newsome Smith, 45, carried out the sick attack on a 22-year-old woman in a room of mirrors at the “swingers’” sex club La Chambre in Sheffield, last Halloween.
He denied rape saying they had consensual sex, but was found guilty by a jury on Thursday.
Judge Peter Kelson QC warned Smith, from London, he faces a jail term and released him on bail to “get his affairs in order”.
Prosecutor Charlotte Baines told the jury during the trial at Sheffield Crown Court: “The allegation occurred in an establishment called La Chambre.
“That is a private members club that’s commonly called a swingers’ club. It is an establishment that opens its doors to members who go with a view to watching or participating in sexual activity if they chose to do so.”
“It’s clear that La Chambre makes no secret of the type of establishment that it is. It is a swingers’ club.
“There are rooms upstairs in the club referred to as the ‘playrooms’. Those rooms are for those individuals who want to engage in sexual activity and they engage with other consenting adults in various types of sexual activity - that’s activity that takes place between consenting adults.”
Smith’s victim, who cannot be named for legal reasons, went to the fancy dress party with two female friends.
Miss Baines said she was a member of the club but never took part in any sexual activity and went there purely to socialise.
Smith had been asked to perform as a kinky cabaret act with two friends dressed as Lily Munster and Harry Potter, and were paid in drink.
During the night, Smith had invited the woman to partake in kinky games - which involved her being put into stocks and having her underwear pulled down.
She said the act was “really embarrassing” and later in the evening the defendant plied the woman and her two friends with drinks.
After the show Smith, who admitted taking Viagra before going to the club, and his friends drank and socialised with the victim and her friends.
He then said “let’s go upstairs and laugh at all the people having sex”, where he then raped the woman in an indoor smoking room “covered in mirrors”.
The victim told the jury she froze during the attack.
She said: “I just felt as though I was paralysed. I was just so scared, I knew what was going to happen. I was just so scared I didn’t event know what to do.”
Following the horrific assault, which the victim was forced to watch in the mirrored-walls, Smith kept her underwear saying he had to “to look after it for her”.
She told the court: “He started having sex with me. I could see everything that was happening. I tried to look away but the walls were covered in mirrors so I had to watch everything.”
The woman told police how she wanted her friends to come back and find her, which they later did.
The complainant told her friends what had happened before alerting staff and going to a nearby police station.
Smith denied the allegation of rape, saying the two had consensual sex and that she had “been flirting with him throughout the evening”.
Smith will be sentenced in September after the preparation of a probation report.