Andrew was set to join the wider royal family at the high-profile event in St Paul’s Cathedral.
The monarch’s disgraced second son stepped down from public life after the furore over his friendship with paedophile billionaire Jeffrey Epstein, and paid millions to settle a civil sexual assault case to a woman he claimed never to have met.
A Buckingham Palace spokesman said: “After undertaking a routine test The Duke has tested positive for Covid and with regret will no longer be attending tomorrow’s service.”
It is understood Andrew saw the Queen in the last few days but has been undertaking regular testing and has not seen her since he tested positive.
The duke was cast out of the working monarchy and no longer uses his HRH style after Virginia Giuffre, who was trafficked by Epstein, accused him of sexually assaulting her when she was 17. The duke denied the claims.
He was pictured earlier this week smiling as he rode through the grounds of Windsor Castle, before the positive Covid test.
He has kept a low profile but accompanied his mother to Prince Philip’s memorial at Westminster Abbey in March.