The couple have been hosting a ceremony at their Windsor estate in Berkshire with a number of stars in attendance.
David and Victoria Beckham, musician Ed Sheeran and actor David Walliams were among the guests.
Mr Furnish and Sir Elton, who have two sons, became civil partners in 2005.
The couple's sons Zachary, who was born in 2010, and Elijah, born last year attended the ceremony.
(BBC News)