The opening ceremony will be at 9.30am. Afterwards His Holiness will cross the road to be greeted by the Archbishop of Southwark outside the cathedral where a short service will follow.
The cathedral event is at 10.30am and will be open to the public.
The day is already special to the cathedral as it is Ascension Day in the Christian calendar.
- The Spirit of Mongolia, a contemporary art exhibition, is being staged at the nearby Walk Gallery to coincide with the opening.
- It is 17 years to the month since His Holiness Pope John Paul visited Southwark's St George's Cathedral. The occasion is depicted in a window on the north side.