Kate, the Princess of Wales, underwent planned abdominal surgery and will remain in hospital for 10 to 14 days, Kensington Palace said.
The princess was admitted to The London Clinic on Tuesday for the procedure.
The operation was successful and she will return home after the two-week period to continue her recovery.
She is unlikely to return to public duties until after Easter.
King Charles III will also be admitted to hospital next week for treatment on his prostate, meaning his public engagements will be postponed, Buckingham Palace said
The Palace refused to confirm what Kate was being treated for but confirmed that the condition was non-cancerous.
“The surgery was successful and it is expected that she will remain in hospital for 10 to 14 days, before returning home to continue her recovery," Kensington Palace said.
"Based on the current medical advice, she is unlikely to return to public duties until after Easter.
“The Princess of Wales appreciates the interest this statement will generate. She hopes that the public will understand her desire to maintain as much normality for her children as possible; and her wish that her personal medical information remains private.
“Kensington Palace will, therefore, only provide updates on her royal highness’s progress when there is significant new information to share.
Catherine Princess of Wales through the years - in pictures
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Catherine, Princess of Wales greets wellwishers after attending the Christmas Day service at Sandringham Church in Norfolk in 2023. All photos: Getty Images, unless otherwise indicated -
Catherine flies a drone as she visits The Queen's Dragoon Guards Regiment for the first time as their Colonel-in-Chief in November 2023 -
Catherine congratulates the England team on their Rugby World Cup quarter final victory over Fiji at Marseille's Stade Velodrome in France, in October 2023 -
Sophie, Duchess of Edinburgh, Princess Charlotte, Prince Louis, Prince William and Catherine on the balcony of Buckingham Palace following the Coronation of King Charles III on May 6, 2023 -
Catherine meets wellwishers during a walkabout on the Mall outside Buckingham Palace before the coronation in May 2023 -
Catherine takes part in a spin class during a visit to Aberavon Leisure and Fitness Centre in Port Talbot, in February 2023 -
Prince George, Prince William, Princess Charlotte, Prince Louis and Catherine attend the Easter Mattins Service at St George's Chapel, Windsor, in April 2023 -
Catherine is driven down The Mall after the funeral of Queen Elizabeth II on September 19, 2022 -
Prince William and Catherine with the Duke and Duchess of Sussex during the Lying-in-State of Queen Elizabeth in the Palace of Westminster in September 2022 -
Catherine and Prince Louis attend the Platinum Jubilee Pageant in June 2022 in London -
Catherine, Prince William and their children on the balcony at Buckingham Palace to watch the RAF flypast during the Trooping the Colour parade to mark Queen Elizabeth's Platinum Jubilee in June 2022 -
Catherine is accompanied by Hollywood star Tom Cruise at the Top Gun: Maverick Royal Film Performance at the Odeon Leicester Square, London, in May 2022 -
Catherine enjoys a slide during a visit to the Lego Foundation PlayLab in Copenhagen, Denmark, in February 2022 -
Catherine takes part in an England training session, after becoming patron of the Rugby Football Union in February 2022, at Twickenham Stadium in London -
Prince William and Catherine attend the Earthshot Prize at Alexandra Palace, London, in October 2021 -
Catherine plays tennis with US Open champion Emma Raducanu at the LTA Centre in Roehampton in September 2021 -
Catherine land yachting at the beach in St Andrews, Scotland, in May 2021 -
Catherine tries her hand at archery on visit to The Way Youth Zone in Wolverhampton in May 2021 -
Catherine visits to the Covid-19 vaccination centre at Westminster Abbey in March 2021 -
The royal couple play a grab-a-teddy game during a visit to Barry Island, South Wales, to speak to local business owners about the effect of Covid-19 on the tourism sector in August 2020 -
Prince William and Catherine try hurling at Salthill GAA club during a visit to Ireland in March 2020 -
Prince William and Catherine visit a settlement of the Kalash people, to learn more about their culture and unique heritage, during a visit to Pakistan in October 2019 -
Catherine accompanies Princess Charlotte as she arrives for her first day of school with her brother Prince George at Thomas's Battersea in London in September 2019 -
Catherine presents Novak Djokovic with the Wimbledon men's singles trophy in July 2019 -
Queen Elizabeth visits the RHS Chelsea Flower Show with Prince William and Catherine in May 2019 -
Prince William, Catherine, Meghan, Duchess of Sussex and Prince Harry arrive for the Christmas Day church service on the Sandringham Estate in 2018 -
Catherine at a state banquet for King Willem-Alexander and Queen Maxima of the Netherlands at Buckingham Palace in October 2018 -
Catherine and Prince William with Prince George, Princess Charlotte and Prince Louis after Louis' christening at St James's Palace, London, in July 2018 -
Prince William and Catherine leave the Lindo Wing of St Mary's Hospital, London, with newborn Prince Louis in April 2018 -
Catherine and Prince William cook with nursery children in Norway, during a visit to Sweden and Norway in February 2018 -
Catherine with four-year-old Rafael Chana on a visit to Great Ormond Street Hospital in London to officially open the Mittal Children's Medical Centre in January 2018 -
Catherine dances with Paddington Bear as she meets the cast and crew of the film Paddington 2 in London in October 2017 -
Catherine plays with Prince George as US President Barack Obama talks to Prince William at Kensington Palace in April 2016 -
In front of the Taj Mahal during the royal tour of India in April 2016 -
Catherine and Prince William on a game drive at Kaziranga National Park in north-eastern India, in April 2016 -
Catherine with her daughter Princess Charlotte at the Church of St Mary Magdalene on the Sandringham Estate for the princess's christening in July 2015 -
Catherine and Prince William at Uluru, also known as Ayers Rock, during a tour of Australia and New Zealand in 2014 -
Catherine with Prince George and Prince William visiting the Natural History Museum in London in July 2014 -
Catherine and Prince William with newborn Prince George, at St Mary's Hospital in London in July 2013 -
Prince Harry, Catherine and Prince William on the set of Diagon Alley from the Harry Potter films during the opening of the Warner Bros Studios in Leavesden, in April 2013 -
Catherine and Prince William celebrate after watching cyclists Philip Hindes, Jason Kenny and Sir Chris Hoy of Great Britain win the gold and set a world record during the London 2012 Olympic Games -
Queen Elizabeth II and Catherine watch a fashion show at De Montfort University, Leicester, in March 2012, during the Queen's Diamond Jubilee tour of the UK -
Prince William and Catherine outside Buckingham Palace the day after their wedding where a helicopter was waiting to fly them off on honeymoon -
Catherine and her sister and maid of honour Pippa Middleton enter Westminster Abbey for the royal wedding on April 29, 2011 -
Prince William exchanges rings with his bride in front of the Archbishop of Canterbury Rowan Williams during their wedding ceremony at Westminster Abbey in April 2011 -
Kate Middleton and Prince William visit Trearddur Bay lifeboat station in Anglesey, Wales, in February 2011, after their engagement in November 2010 -
Prince William and Kate Middleton cheer the English team during the RBS Six Nations Championship rugby match between England and Italy at Twickenham in 2007 -
At the Gatcombe Park Festival of British Eventing in Gloucestershire, in 2005 -
Kate Middleton during her graduation at St Andrews University in June 2005. She and Prince William met as students at the university in Scotland. PA -
Kate Middleton, front left, in a rounders team photo during her time at St Andrew's School in Pangbourne, Berkshire. She attended the school from 1986 until 1995 -
Kate on a family holiday in the Lake District when she was three years old
“The Princess of Wales wishes to apologise to all those concerned for the fact that she has to postpone her upcoming engagements. She looks forward to reinstating as many as possible, as soon as possible.”
The Prince and Princess of Wales have solidified their position as being among the most popular members of the royal family since Prince Harry and Meghan’s stormy departure to California in 2020.
The princess, in particular, is a reliable royal in the public eye and is increasingly undertaking solo public engagements.
Her last public appearance was the annual Christmas Day service at Sandringham.
The princess, who celebrated her 42nd birthday earlier this month, met and began dating Prince William, 41, now the Prince of Wales, at St Andrews University, and married him in Westminster Abbey in 2011, becoming the Duchess of Cambridge and also a future queen.
The mother of three missed out on a trip to Singapore with her husband last autumn for the Earthshot Prize awards, staying at home with 10-year-old son Prince George.
The couple did not embark on a joint official overseas tour in 2023, taking a back seat to allow King Charles and Queen Camilla to embark on their inaugural travels.
They are reportedly planning to travel to Italy this spring.
