Violent Thomas Holmes also mocked the taxpayer for paying for his meals while he serves a 13-year sentence for repeatedly raping a woman.
“He should have all privileges stopped - he is glorying in his crime and obviously has no remorse,” said Pauline Carruthers, founder of the Scarborough sex abuse charity Hope.
The Ministry of Justice has now launched a probe into the forbidden post, which could result in Holmes being forced to serve another two years at HMP Hull.
Prisoners are banned from using mobile phones and social media while locked up, and face tough punishments if found with them.
But Holmes’ boastful post has sickened former friends, who say he is an insensitive, remorseless “monster”, who has used social media to laugh in the face of justice.
“He probably thinks it’s hilarious, but it just shows there isn’t an ounce of remorse in his body,” said one Facebook friend.
The 43-year-old rapist, originally from Rochdale, posted a picture of The Scarborough News’ article on his conviction, along with the caption: “Sorry all not been in touch and won’t be for a while but I’m on a long earned holiday in Hull.”
But his former friend added: “Like many people I hadn’t even realised he’d been locked up, and if I’d known what he’d done I’d have unfriended him in a heartbeat.
“For me he’s heartless, and clearly doesn’t care one bit about what his poor victim must feel .
“Prison should be extra hard for him, so for him to call it a holiday isn’t going to make anybody laugh - everybody now just thinks he’s disgusting.”
Facebook has now removed his account, despite some of his family claiming it had been hacked as he languished inside the Category B prison.
He was imprisoned there in May after his tough sentence for what a detective claimed was one of the worst cases she’d ever worked on.
Holmes, of Oxcliff, admitted four counts of rape in what York Crown Court heard were “horrific” attacks over a three-day period, designed to degrade and humiliate his victim - as she recovered from a serious illness.
Hope’s Pauline Carruthers, whose charity helps victims of sexual abuse and rape, has questioned how Holmes was allowed to not only post on Facebook, but spend almost a day surfing the web and posting statuses before the alarm was raised.
“I thought the whole point of prison was to cut criminals off from the outside world as punishment,” she said, adding: “His victim is being victimised by the authorities allowing him a voice.” It’s the latest embarrassment for the Prison Service, which last week launched a separate investigation after dozens of prisoners held a boozy rave in a cell - before uploading the video onto Facebook via a smuggle mobile phone.
The service said mobiles are deemed contraband in all prisons, and guards confiscate any found in cells.
It adds that it’s pumping cash into new technology to “detect and disrupt” their use, which can lead to further prosecution and a prison sentence of up to two years.
But sources claim use is “rife” in British jails, with recent figures revealing over 20 phones a day are seized.
A Prison Service spokesperson said: “We are taking immediate action to have this Facebook profile removed.
“Prisoners are banned from using mobile phones and social media.
“Those found to be breaking the rules will face tough punishments, including being stripped of privileges and having time added to their sentence.”