The couple are set to tie the knot on May 19, 2018 at St. George's Chapel, Windsor Castle and Elton has made arrangements to ensure he is there to mark the big day.
Speaking to The Sun newspaper last month about the nuptials, he said: "I don’t know. I haven’t even been - no one’s been asked. I’m playing in Vegas so I don’t know what’s going to happen. It will be nice because I love him very dearly."
However, now Elton has cancelled two dates - Friday May 18 and Saturday May 19 - of his Las Vegas residency so he can be there at the couple's big day.
Kensington Palace previously confirmed the unusual date Harry and Meghan's wedding, which will take place on the weekend despite royal tradition to hold weddings midweek.
The spokesperson said: "The marriage of His Royal Highness Prince Harry of Wales and Ms. Meghan Markle will take place at St. George's Chapel, Windsor Castle in May 2018. Her Majesty The Queen has granted permission for the wedding to take place at the Chapel. The Royal Family will pay for the wedding. Further details about the wedding will be announced in due course."
Elton previously opened up about how he "could tell" that Harry was in love when the pair met up months ago.
He said: "I spent some time with him in Sicily last summer and I could tell that he was totally in love, and he didn't really discuss much personally but he said 'I'm in love' ... and I thought, good for you.
"Both those boys seem to have been ecstatically happy," he said of Harry and big brother William, "and that's all you want people to be."