Prince Charles will walk Meghan Markle down the aisle on Saturday when she marries Prince Harry, Kensington Palace has said.
Meghan’s father, Thomas, is unable to attend the wedding, after undergoing heart surgery.
The Prince of Wales was “pleased to be able to welcome Ms Markle to the Royal Family in this way,” the palace added.
Prince Harry’s grandfather, the Duke of Edinburgh, will also attend the wedding, Buckingham Palace confirmed.
Prince Philip, 96, has been recovering from a hip operation.
The bride’s mother, Doria Ragland, will take her daughter to the wedding at St George’s Chapel in Windsor.
Ms Ragland has arrived at Windsor Castle to meet the Queen for the first time, accompanied by Meghan, 36, and Prince Harry, 33.
She has already been introduced to Prince Charles and the Duke and Duchess of Cambridge.
The ceremony begins at 12:00 BST and will be broadcast to the world.
Mr Markle had been due to arrive in the UK earlier this week, but became caught up in controversy over the apparent staging of photographs with the paparazzi.
Speaking to the BBC from Windsor, American celebrity news site TMZ’s Sean Mandell said he had spoken to Mr Markle on Wednesday and that he was “doing well” and “recovering from surgery”.
Mr Mandell – who broke the story – said Mr Markle realised on Tuesday that he would not be travelling to Windsor.
“Chest pains were really being exacerbated by the emotional strain he was under,” he said.
“When doctors told him he needed to have surgery, he decided he needed to heed that advice, despite the fact he wanted to be here in Windsor for Meghan.”
“He definitely feels he’s been mis-characterised,” Mr Mandell added. “That’s why he felt the need to speak out when I reached him.”
Ms Markle released a statement on Thursday saying she hoped her father could be given space to focus on his health.
Meghan will spend her last night before the wedding with her mother at the luxury Cliveden House Hotel, in Buckinghamshire, about nine miles north of Windsor Castle.
Prince Harry will be staying 15 miles away at the Dorchester Collection’s Coworth Park in Ascot, with his brother, the Duke of Cambridge.
In Windsor, royal fans have been arriving throughout the week, with the rehearsal of the carriage procession on Thursday drawing hundreds of children, parents and pets keen to embrace the party mood.
About 250 members of the armed forces are expected to take part on Saturday and up to 100,000 people are expected to line the procession route.