The King and Queen were joined by the Duke of York at the traditional Easter Sunday service at Windsor Castle.
Andrew arrived at St George’s Chapel, Windsor Castle, with the Princess Royal, his ex-wife Sarah, Duchess of York and Anne’s husband Vice Admiral Sir Tim Laurence.
He quickly entered the chapel ahead of his sister Anne as she spoke with the Dean of Windsor, the Right Rev Christopher Cocksworth outside.
The duke has not been pictured at a formal royal family event since last Easter.
He had disappeared from public life after stepping down from official duties.
Charles and Camilla waved and smiled at crowds who were gathered outside the chapel.
Also attending the service was the Duke and Duchess of Edinburgh and their son James – the Earl of Wessex, Princess Eugenie and her husband Jack Brooksbank and Princess Beatrice and her husband Edoardo Mapelli Mozzi.
However, the Prince and Princess of Wales are spending the weekend with their children in Norfolk.
The Waleses, who have a country home, Anmer Hall, on the Sandringham estate, missed the annual service last year after Kate, who is now in remission, was diagnosed with cancer.
Andrew missed the royal family’s traditional Christmas gathering at Sandringham last year amid the controversy surrounding his links to an alleged Chinese spy.
He stepped down from public life after criticism over his friendship with convicted sex offender Jeffrey Epstein – and a few years later paid millions to settle a civil sexual assault case with Virginia Giuffre, a woman he claimed never to have met.
It followed his Newsnight interview in 2019 when he said he “did not regret” his friendship with Epstein, who had trafficked Ms Giuffre, and was heavily criticised for failing to show sympathy with the sex offender’s victims.
The duke announced at the time he would be “stepping back from public duties for the foreseeable future” and disappeared from a string of high-profile national events involving the monarchy.
Queen Elizabeth II later stripped him of his honorary military roles, remaining royal patronages and he gave up his HRH style in a dramatic fallout from his civil sex case.