The eldest daughter of the Duke of York and Sarah, Duchess of York is set to wed millionaire property tycoon Edoardo Mapelli Mozzi after a whirlwind romance.
The pair began dating in autumn 2018, and were soon being tipped to walk up the aisle.
Buckingham Palace said in a statement: "The Duke and Duchess of York are delighted to announce the engagement of Her Royal Highness Princess Beatrice of York to Mr Edoardo Mapelli Mozzi.
"Her Royal Highness and Mr Mapelli Mozzi became engaged while away for the weekend in Italy earlier this month.
"The wedding will take place in 2020."
Beatrice's sister Princess Eugenie posted her congratulations on Instragram, saying: "Beabea - wow! I'm so happy for you my dearest big
sissy and dear Edo.
"It's been a long time coming and you two are meant to be. (camera emoji) by me!! "
Beatrice - the Queen and the Duke of Edinburgh's granddaughter - is ninth in line to the throne, and a cousin of the Duke of Cambridge and the Duke of Sussex.
Only the first six people in the line of succession have to obtain the Queen's permission to marry, but it is likely the monarch would have been among the first to be told by her granddaughter of the impending nuptials.
Beatrice is following in the footsteps of her younger sister Eugenie by getting married.
Eugenie was treated to a glittering, star-studded wedding at St George's Chapel, Windsor Castle in October 2018.
The ceremony, which was attended by 800 guests, was televised and Eugenie and husband Jack Brooksbank enjoyed a carriage ride through Windsor afterwards.
They continued their celebrations with a weekend of festivities at the nearby York family home Royal Lodge.
Beatrice's father Andrew has faced a storm of controversy in recent weeks over his links to paedophile financier Jeffrey Epstein.
Virginia Giuffre, who alleges she was a victim of Epstein, has said she was forced into sexual encounters with the duke.
Buckingham Palace and Andrew have strongly denied the accusations.
Andrew and his ex-wife Sarah, who was previously outcast from the royals following her famous "toe-sucking scandal", will want to ensure Beatrice is given the same special treatment on her big day as her sister.
Her wedding will be the fourth royal one in recent years, following the Duke and Duchess of Sussex's and then Eugenie's in 2018, and Prince and Princess Michael of Kent's daughter Lady
Gabriella Windsor's to Tom Kingston in 2019.
All three took place in the gothic 15th century St George's Chapel at Windsor Castle in Berkshire, with Beatrice likely to be offered the chance to marry in the same venue by the Queen.
Other options could include Canongate Kirk in Edinburgh, where Beatrice's cousin Zara Phillips married Mike Tindall.
It is unlikely the princess would choose the higher profile Westminster Abbey in central London where her parents and the Duke and Duchess of Cambridge married.
Beatrice, who split from her long-term love Dave Clark in 2016 after 10 years together, appeared with property developer Edoardo, who is known as Edo, at a [email protected] event at St
James's Palace in London, hosted by Andrew in June.
Edoardo is the son of former Olympic skier Count Alessandro Mapelli Mozzi and Nikki Shale, is a count himself, and has been a friend of the Yorks for some time.
His stepfather was Christopher Shale, a senior Tory and a close friend of former prime minister David Cameron. He died from heart disease at the Glastonbury Festival in 2011.
Beatrice and her family attended the funeral.
Edoardo has a young son named Wolfie with ex-fiancee Dara Huang.
The princess is said to have begun dating Edoardo after meeting him again at Eugenie's wedding.
Beatrice is not a full-time working royal and is described on Andrew's website as working in business.
She hit the headlines with the unusual "pretzel" hat which she wore to William and Kate's wedding in 2011.
It was likened to everything from a toilet seat to a cat flap and Facebook pages sprung up in its honour, attracting thousands of followers.
She auctioned the headwear on eBay for charity, raising more than £81,000 for good causes.
Princess Beatrice Elizabeth Mary of York was born fifth in line to the throne on August 8, 1988.
She has a number of royal patronages including Forget Me Not Children's Hospice, the Teenage Cancer Trust and the Helen Arkell Dyslexia Centre.