There will be a weekend royal walkabout and a party for about 5,000 in the centre of the Scottish capital.
The new moderator of the General Assembly, Rev John Chalmers, will also receive the ceremonial cross and ring from outgoing Moderator Rt Rev Lorna Hood today.
Lord High Commissioner to the General Assembly Prince Edward, Earl of Wessex, and his wife Sophie, Duchess of Wessex, will take part in a historic procession and the prince will also attend this year's Heart and Soul festival tomorrow in Princes Street Gardens.
As Lord High Commissioner, the prince will observe the assembly as the Queen's representative, reporting back to Her Majesty.
Prince Andrew was the last royal to hold the role in 2007.