The private, 40-minute ceremony will be conducted by the Archbishop of Canterbury, Justin Welby, in the Chapel Royal at St James’s Palace at 4pm on Monday.
Eleven-week-old Louis, who is fifth in line to the throne, will be dressed in the same frilly cream gown used by his older brother and sister, George and Charlotte.
It is a replica of a garment made for Queen Victoria’s eldest daughter, also called Victoria, in 1841.
While Kensington Palace is yet to release a guest list, royal christenings are usually small, family affairs.
The Duke and Duchess of Sussex, who married in May, are likely to be there.
Meghan was christened and confirmed by the archbishop in the same chapel in March.
Kate’s pregnant sister, Pippa Matthews, is also expected to be present.
Louis’ godparents will be announced on the day, but judging by George and Charlotte’s christenings, they are likely to be close friends and confidantes of William and Kate.
There is speculation that William’s outgoing private secretary, Miguel Head, could be chosen to perform the role.
Louis weighed 8lb 7oz when he was born on 23 April – St George’s Day.
His father said he had “thrice the worry now” when he left hospital with Kate to take the infant home to Kensington Palace.
Early on, Louis appeared to be a model baby.
Two days after he was born, William said he was sleeping “reasonably well so far, so he’s behaving himself, which is good”.
Louis is the Queen and Duke of Edinburgh’s sixth great-grandchild.
Her Majesty and Prince Philip now have a seventh too, following the arrival of Lena Tindall last month.