The 71-year-old star is booked to sing at the event on Saturday after he quietly cancelled two of his last Vegas Shows, celebrity news website TMZ said.
It comes after he performed his single Candle in the Wind at Harry’s mother Princess Diana’s funeral in 1997 after she died in a car accident.
Elton is set to entertain the star-studded guestlist at this Saturday’s event, but it was not immediately if he will perform at the ceremony or at the reception that follows it.
The singer cancelled two of his shows in Las Vegas that freed him up for the weekend of the royal wedding, which is taking place at St George’s Chapel in Windsor.
He was due to play concerts at The Colosseum at Caesars Palace on Friday May 18 the following day but is now expected to head to the wedding with his partner David Furnish.
The reports emerged as a rehearsal for the wedding was due to take place in Windsor later today.
Some 250 members of the armed forces are expected to take part in Saturday's festivities, lining the streets as the newlywed Harry and Ms Markle head on a 25-minute carriage ride through the town.
After months of planning, Thursday's dry-run will give organisers a chance to put some finishing touches to the global event.