Kensington Palace has not released the guest list, but newlyweds the Duke and Duchess of Sussex are expected to attend, along with Kate's pregnant sister Pippa Middleton and their brother James Middleton.
The christening itself is quite the family tradition, Royal Central U.K. notes, adding Prince Louis also wore a replica of the now-famous Honiton lace christening gown.
The Ordinance, which lasted about 40 minutes, was conducted by the Archbishop of Canterbury Justin Welby, who as head of the Church in England, involved in nearly every important event in the life of the British Royal family, from a wedding to a christening.
Queen Elizabeth, 92, and her 97-year-old husband Prince Philip attended the christenings of Louis' older siblings Prince George and Princess Charlotte. The original is now too fragile to wear, so the queen commissioned the copy from her royal dressmaker, Angela Kelly.
Prince George and Princess Charlotte each held on to their dad's hands as he guided them towards the chapel.
Kate looked happy and at ease during one of her rare official appearances since the birth of Prince Louis. Water from the River Jordan will be used during the baptism.
He is fifth in line to the throne.
In the same way as the eldest son of the Duke and Duchess of Cambridge Prince George, little Louie was baptized in the chapel Royal St JaME's Palace.
The Duke and Duchess of Cambridge has an emotional attachment with the anthem titled "This is the day which the Lord hath made" as it was composed in 2011 for their royal wedding.
The christening will be a small affair for immediate family, the godparents and their spouses.
Mr. Nicholas van Cutsem is one of William and Harry's oldest friends.
Aubrey-Fletcher is yet another longtime friend of William's, according to People.