But the organisers are declining to say which other celebrities will attend the £30,000-a-table event.
Last year's event raised more than £11m for the charity's projects, which include funding medics to treat people with Aids in South Africa and helping orphans in eastern Europe.
"We always like to do better year on year," said Paul Bernstein, managing director of the charity.
"Our donors are accustomed to the world of investment. People who move in that world expect a return."
Ark trustee Stanley Fink is chief executive of the biggest hedge fund in the world, and other City financiers are expected to feature strongly in the 1,000 attendees.