Andrew Mountbatten Windsor no longer appears on the official roll of the peerage in the UK, marking a key step in formally removing his titles.
Buckingham Palace said his name had been struck from the roll after King Charles III took the dramatic decision to formally strip his brother of his Prince and Duke of York titles and HRH style, a move that effectively ends his public life.
Dukes, including the Duke of York, are listed on the roll of the peerage maintained at the Crown Office and, as Lord Chancellor, David Lammy is responsible for maintaining it.
Mr Lammy, who is Britain's Deputy Prime Minster, was due to be sent royal warrants by the King to strike the Duke from the roll, as well as his Prince title and HRH style. The subsidiary titles are similarly affected.
It is not clear when the move to strike Andrew from the roll took place.
The disgraced royal, whose friendship with convicted sex offender and financier Jeffrey Epstein led to his downfall, will effectively have the status of a commoner and be known as Andrew Mountbatten Windsor.
The family of Virginia Giuffre said she had "brought down a prince" after Charles' decision.
Andrew has also agreed to leave Royal Lodge in Windsor.
The monarchy had come under increasing pressure to resolve the issues around Andrew, foremost his property arrangements, amid growing calls for him to give up Royal Lodge after it emerged he was paying a "peppercorn" rent.
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As the eyes of the world remain fixed on the 30-bedroom mansion, it is unclear when Andrew will leave.
He is to move into an undisclosed private residence on the Sandringham Estate in Norfolk as soon as practicable, it is understood.
Andrew had tainted the reputation of the royal family with his association with Epstein and, for many years, was dogged by allegations he sexually abused Ms Giuffre, who took her own life in April, after she was trafficked by the financier.
He has strenuously denied the allegations.
In a statement given to the BBC, Ms Giuffre's family said she had "never stopped fighting for accountability".
It said: "Today, an ordinary American girl from an ordinary American family brought down a British prince with her truth and extraordinary courage.
"Virginia Roberts Giuffre, our sister, a child when she was sexually assaulted by Andrew, never stopped fighting for accountability for what had happened to her and countless other survivors like her.
"Today, she declares a victory. We, her family, along with her survivor sisters, continue Virginia's battle and will not rest until the same accountability applies to all of her abusers and abetters, connected to Jeffrey Epstein and Ghislaine Maxwell."
Speaking to BBC Newsnight, Ms Giuffre's brother Sky Roberts thanked Charles for the Buckingham Palace statement that mentioned "thoughts and utmost sympathies" with "victims and survivors of any and all forms of abuse".
He added: "But it's not enough, it's not enough, we have to have some sort of investigation that goes further into this."
It is understood that the unprecedented move was taken by Charles in light of the serious lapses in judgement his brother made and Charles was supported in his decision by the royal family, including Prince William, with Andrew not objecting.
William was put in an untenable position when he appeared to be ambushed by Andrew during the Duchess of Kent's recent funeral, with the disgraced royal trying to talk to his nephew, who barely acknowledged him.
There have been reports that William wanted the matter resolved quickly and his uncle out of Royal Lodge by 5 November, as William is due to move his young family to their forever home at Forest Lodge, near Andrew's home in the coming days.
Andrew will move as soon as practicable to an undisclosed property on Charles's Sandringham estate in Norfolk, with the accommodation privately funded by Charles, who will also make private financial provisions for his brother.
The former prince had a "cast-iron" lease for Royal Lodge and only after negotiations with the King's representatives did he agree to serve formal notice yesterday to surrender the lease, which had more than 50 years left to run.
Any funds Andrew is due for the early surrender will be a matter for the Crown Estate and may be affected by the £7.5 million he spent renovating the home.
Sarah Ferguson lived with her ex-husband Andrew at Royal Lodge but will not be housed by Charles and will have to find a new home.
Buckingham Palace said in a statement: "His Majesty has today initiated a formal process to remove the style, titles and honours of Prince Andrew.
"Prince Andrew will now be known as Andrew Mountbatten Windsor. His lease on Royal Lodge has, to date, provided him with legal protection to continue in residence.
"Formal notice has now been served to surrender the lease and he will move to alternative private accommodation. These censures are deemed necessary, notwithstanding the fact that he continues to deny the allegations against him.
"Their Majesties wish to make clear that their thoughts and utmost sympathies have been, and will remain with, the victims and survivors of any and all forms of abuse."
The latest development in the long-running controversy comes after focus intensified on Charles’s brother after he attempted to draw a line under Ms Giuffre's allegations by giving up his dukedom and other honours earlier this month, ahead of the publication of Ms Giuffre's posthumous memoirs.
But Andrew was instead swamped by criticism that has focused on his property, with some MPs eager to debate the issue in parliament.
