The Prince of Wales will accompany Meghan Markle down the aisle at her wedding to Prince Harry, Kensington Palace said.
In a statement, Kensington Palace said: "Ms Meghan Markle has asked His Royal Highness The Prince of Wales to accompany her down the aisle of the Quire of St George's Chapel on her Wedding Day. The Prince of Wales is pleased to be able to welcome Ms Markle to The Royal Family in this way."
Ms Markle has asked The Prince of Wales to step in, as her father Thomas Markle recovers from heart surgery in the United States.
"Sadly, my father will not be attending our wedding," Meghan said in a statement released on Thursday.
"I have always cared for my father and hope he can be given the space he needs to focus on his health.
"I would like to thank everyone who has offered generous messages of support.
"Please know how much Harry and I look forward to sharing our special day with you on Saturday."
The star's mother Doria Ragland had been tipped to perform the role.
But unlike Ms Ragland, Harry's father is vastly experienced at appearing at large-scale public events amid intense scrutiny.
He also performed the duty for Alexandra Knatchbull, the daughter of his close friend, Lord Brabourne, in 2016.
It is reported that Harry was involved in discussions with his fiancee about who should take on the important role on the big day.