The King and the Queen Consort will sit in the ornate Canada Club chairs in the front row of the south lantern.
Camilla will be seated next to the Princess Royal, then Vice Admiral Sir Timothy Laurence, the Duke of York and the Earl and Countess of Wessex.
Across the aisle will be the Prince and Princess of Wales, Prince George and Princess Charlotte, and then Peter Phillips and Zara and Mike Tindall.
Directly behind the King will be the Duke of Sussex, with the Duchess of Sussex behind Camilla. Meghan will be sitting next to Princess Beatrice.
Heads of state, prime ministers and presidents, members of European royal families and key figures from public life are also among the 2,000 mourners gathering at the abbey for the service.
US President Joe Biden will be 14 rows back on the south transept behind the Polish leader and in front of the Czech Republic. The First Lady Jill Biden will be next to Switzerland.
Directly across the aisle from Mr Biden’s place, the seat was labelled the Republic of Korea.
Leaders attending include Australian Prime Minister Anthony Albanese, New Zealand Prime Minister Jacinda Ardern and Canadian Prime Minister Justin Trudeau, as well as European leaders including French President Emmanuel Macron and European Commission President Ursula von der Leyen.
But invitations were not sent to Russia and Belarus due to the invasion of Ukraine while Taliban-ruled Afghanistan, Myanmar’s military junta and Syria’s Bashar Assad were also excluded.