Prince Louis has been christened during a 40-minute service at the Chapel Royal at St James' Palace in London.
After the ceremony had taken place, the family emerged from the Chapel Royal, with Charlotte carefully clutching the order of service under her arm and sweetly waving to the photographers again.
The Duke and Duchess of Sussex will also be guests, as will Kate's brother James Middleton, and Kate's pregnant sister Pippa with husband James Matthews - the brother of former Made in Chelsea star Spencer Matthews. He is fifth in line to the throne. For the christening of Prince Louis this week, Harry gave his nephew the best present he could find. Meghan Markle wore an olive green dress by Ralph Lauren and a matching Stephen Jones hat.
There they would be joined by the Duke and Duchess of Cornwall and the Duke and Duchess of Sussex along with other guests. The robe is a family heirloom that dates all the way back to 1841, when Queen Victoria's oldest daughter wore it for her christening. Prince George and Princess Charlotte were in attendance sure not to miss their younger brother's big day. James and Prince William have been close ever since they attended Eton College together - William was even an usher at his wedding to Laura - and Laura's family is close with the Middletons.
The Duke and Duchess of Cambridge chose hymns O Jesus, I Have Promised and Lord of All Hopefulness for the ceremony. He will be christened in the Chapel Royal of the St. James's Palace in central London, close to Buckingham Palace, the BBC said.
Queen Elizabeth II has returned to the royal spotlight one day after her absence from great-grandson Prince Louis' christening, with the monarch attending the 100th birthday celebrations of the Royal Air Force on Tuesday.
While William was also dressed in full RAF uniform, his ensemble differed slightly to Harry's by wearing a blue sash across his body.