Louis' godmothers are Lady Laura Meade, Hannah Carter, and Lucy Middleton.
Another well-known name to appear on the list of godparents includes Guy Pelly, who is the owner of the London nightclub Tonteria.
The Queen and the Duke of Edinburgh were unable to attend the family ceremony.
Her majesty the Queen was also in attendance dressed as stylishly as she always does in strong bold colours.
The christening of Prince Louis was held in the Chapel Royal at London's St James's Palace on Monday afternoon and the royal family looked in great spirits - and totally stylish - for the special event.
It may have been her baby brother's christening but - once again- Princess Charlotte was the star of the show.
They were joined by grandparents Michael and Carole Middleton, uncle James Middleton and pregnant aunt Pippa, who attended with her husband James Matthews.
Louis will have six godparents, including close friends and family members of the royal couple.
Princes Harry and William were always fond of English author Alan Alexander Milne (known as A.A. Milne professionally), so a book about Pooh Bear sounded like the right way to start the first-editions library.
Sure, Queen Elizabeth may have appointed Prince Charles as her successor, but one question still remains: What will Kate Middleton's title be when he becomes king? Several took to social media to comment on the "cheeky" siblings. "And he, in this sort of just William way, said to his mother, just below the pink cap, 'I don't like 'tographers, '" recounted Wharfe.
Prince Louis' robe was a replica of the lace and satin dress made for Queen Victoria's eldest daughter in 1841, and was also worn by Prince George and Princess Charlotte.
Following the church service, the guests were invited to a private tea at Clarence House, residence of Prince Charles and his wife Camilla.
After a handsome ceremony at the St George's Chapel, the two left in a carriage to take a tour around Windsor.