The 'Love Me Like You Do' hitmaker - who sang at the reception of the prince's brother, Prince William to Duchess Catherine in 2010 - will reportedly be in attendance at her old friend's nuptials at Windsor Castle in May, and will be accompanied by her boyfriend Caspar Jopling, 26.
The 31-year-old singer was rumoured to have shared a kiss with Harry after a polo match in June 2016, and she'll join two of his other former lovers, Chelsy Davy, 32, and Cressida Bonas, 29, in receiving an invitation to his big day.
A source told The Sun newspaper: "Ellie has stayed good pals with Harry and is obviously really excited.
"She has no plans to perform this time but just wants to celebrate her friend's marriage.
"Princess Eugenie's also a close friend, so she'll fit right in."
Other celebrity guests expected to be at the funeral include Sir Elton John, who famously sang at the funeral of Harry's mother, Princess Diana, and the Spice Girls.
Mel B recently claimed the reunited girl band will be performing at the wedding.
A post shared by elliegoulding(@elliegoulding) on Mar 6, 2018 at 7:46am PST
She said: "I'm going. I don't know if I should've said that. Us five Spice Girls did [get an invitation]. Why am I so honest?"
Mel wouldn't divulge what the invitations to the big day looked like as she felt that was "too personal", but talk quickly moved on to whether or not the band would be performing at the reception after Prince Harry, 33, and Meghan, 36, have officially tied the knot.
The star didn't verbally confirm the news, but once the question was asked she threw her cue cards into the air, which prompted the show's hosts to cheer.
Mel then added: "I swear I'm just ... I need to go, I'm going to be fired. I'm gonna be fired."
However, her bandmate Mel C, later insisted her pal was joking.
She said: "I've met [Harry's dad] Prince Charles lots of times. I'm going to ask him where my invite is because I haven't got mine yet, obviously Mel B said she has hers. I think Mel was just kind of having a bit of a joke. There are no plans to go to the wedding at the moment."