As usual, Prince George won over fans with cuteness.
The little prince gave adorable looks to the crowd.
And won hearts by waving.
The small private service was also attended by the Queen and the Duke of Edinburgh, Prince Charles and the Duchess of Cornwall, the Duchess of Cambridge's parents, Carole and Michael Middleton, and her siblings, Pippa and James.
The Queen looked bright and summery in pastel pink.
Princess Charlotte's five godparents, Sophie Carter, James Meade, Adam Middleton, Laura Fellowes, and Thomas van Straubenzee, and their partners were the only other guests in attendance. The godparents were named by the palace earlier on Sunday morning.
Thomas van Straubenzee is one of William's oldest school friends and gave a speech at the Duke and Duchess' wedding. Sophie Carter and James Mead are friends of the royal couple.
Princess Charlotte was baptised using the Lily Font, once owned by Queen Victoria and usually kept among the crown jewells.
When it was announced where the water had come from, many people on Twitter felt it was an unnecessary extravagance.
And said it was wasteful.
Others simply joked about it.
The baby princess wore a replica of the Victorian lace gown used at all royal christenings, re-made by the queen's dressmaker, Angela Kelly.
Members of the public were invited to watch the royal family arrive at the event in an area named the "paddock".
Well-wishers began arriving early on Sunday morning to secure a good spot.
They battled off rain to get a glimpse of the royal family.
Following the ceremony, photographer Mario Testino will take the official christening pictures. Testino shot William and Kate's official engagement portraits, as well as the pictures of Prince George's christening.
Laura Silver is a reporter for BuzzFeed News and is based in London.