Elton John weds long-time partner

British pop singer Elton John has married his partner of 21 years, David Furnish.

Sir Elton John has confirmed he and his longtime partner David Furnish will marry today. (AAP)

British pop legend Elton John has married long-time partner David Furnish at their Windsor estate, the ninth anniversary of their civil partnership, with the singer posting evidence on social media.

The 67-year-old singer posted a picture on photo-sharing website Instagram on Sunday of himself and Furnish brandishing pens as they signed a form.

"That's the legal bit done. Now on to the ceremony!" said the caption.

The star-studded ceremony will take place at their Windsor home, near London, close to the castle beloved by Queen Elizabeth II.