The couple have once again turned to fashion photographer Chris Allerton to capture the moment on Saturday.
He took their wedding photographs and other images of the couple with their baby.
Some of Mr Allerton’s pictures will be released following the ceremony.
It is understood to protect the privacy of the godparents, who are thought to be private individuals and not public figures, their names will not be released.
But the duke and duchess’ decision to keep their baby’s christening a private event, without the press or public able to see any elements of the day, has been criticised by some commentators.
Buckingham Palace said in a statement: “Archie Harrison Mountbatten-Windsor will be christened in a small private ceremony by the Archbishop of Canterbury in the Private Chapel at Windsor Castle on Saturday 6th July.
“The Duke and Duchess of Sussex look forward to sharing some images taken on the day by photographer Chris Allerton.
“The godparents, in keeping with their wishes, will remain private.”
Royal biographer Penny Junor has labelled the couple’s decision to exclude the press and public a mistake, saying well-wishers would want to share in their big day.
Ms Junor said: “We’re not asking for Archie to become public property but to be able to share in the pleasure of his christening, I think it is only fair to give the public that pleasure.”
The property, close to Windsor Castle, underwent major work to turn five properties back into a single residence for the couple and their baby – with all fixtures and fittings paid for privately by the duke and duchess.
It is understood the Queen will not be attending the christening, as she has prior engagement, but the other expected guests include the Prince of Wales, Duchess of Cornwall, Duke and Duchess of Cambridge and Meghan’s mother Doria Ragland.
Among those rumoured to be chosen as godparents are Meghan’s best friend the Canadian stylist Jessica Mulroney and close confidant Benita Litt, while Harry’s old schoolmates, brothers Thomas and Charlie van Straubenzee, could be picked along with Jake Warren, son of the Queen’s thoroughbred bloodstock adviser John Warren.
But some of the duchess’ famous friends may also be given the honour, from tennis star Serena Williams – who is competing at Wimbledon and due to team up with Sir Andy Murray in the mixed doubles, to lawyer Amal Clooney wife of Hollywood star George Clooney.
Harry Aitkenhead, from bookmakers Coral, said: “We’re just days away from knowing who will be Archie’s godparents and Jessica Mulroney appears to be a banker.
“She’s heavily odds on to be given the honour, and with royal children often having a few godparents we have also made Harry’s close friend Charles Straubenzee too.”