According to the Daily Mail, a 'shocked' Goulding received a personal invite from the couple and will be the only singer to perform at the Buckingham Palace event tomorrow night.
"Ellie was knocked off her feet when she received the invitation to perform for Prince William and Kate - and was so hugely honoured when they said they were both big fans of her music," a source told the paper.
"She still can't quite believe that she will perform for the Royal newlyweds, all the young Royal guests and their friends, it hasn't sunk in yet."
The 24-year-old is expected to perform a selection of tracks from her debut album Lights along with her chart-topping cover of Sir Elton John's 'Your Song'.
Prince William will marry Kate Middleton at Westminster Abbey tomorrow morning.
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Watch Ellie Goulding's video for 'Your Song' below: