The duke and duchess confirmed the service would take place on July 9 at the Chapel Royal at St James's Palace, London.
The third son of Prince William and his wife Kate, Duchess of Cambridge was born April 23 and is fifth in line to the throne.
Reverend Welby, who occupies the most senior bishop role in the Church of England, is no stranger to royal baby baptisms; he christened Prince George in October 2013 and Princess Charlotte in July 2015, per People.
The world will get a glimpse of the newest royal prince very, very soon.
At the event, the young princess was seen leaping around with a pair of sunglasses, while also showing off her acrobatic moves.More news: Macedonia deal signed, protests in Skopje - English
"Judging by the previous christenings, and the importance of the day for the family, Louis' christening will be a private affair, perhaps no surprise there".
Prince William has revealed that Princess Charlotte is already "obsessed" with fashion - after being gifted a pink satchel embossed with her name.
Members of the Royal Family will gather at the chapel to celebrate the christening of their youngest member, Louis.
Newlyweds the Duke and Duchess of Sussex are likely to attend the family celebration.
Guests can expect to chow down on a slice of William and Kate's wedding cake, which was a fruit cake envisioned by Fiona Cairns.