The Duke and Duchess of Sussex’s daughter has been christened at the couple’s home in California.
Princess Lilibet Diana, who was born to Prince Harry and Meghan in June 2021, was baptized on Friday.
The announcement is the first time she has been publicly called a princess and confirms that Harry and Meghan will use the royal titles for their children.
The couple’s spokesman said members of the royal family were invited to the christening.
Although she was not a princess by birth because she was not a granddaughter of the monarch, she became entitled to that title when King Charles ascended the throne.
Buckingham Palace has said the royal website – which currently shows her and brother Archie with the titles of Miss and Champion – will “be updated in due course” to reflect the title.
Lilibet is the second child of Harry and Meghan, who moved to the US after stepping down as working royals in 2020. Their son Archie was born in May 2019.
The BBC understands members of the royal family were invited to the christening, but it appears none attended.
It is understood that Harry and Meghan want their children to decide for themselves whether they want to use their titles when they are older.
The couple will not use the titles in conversation, the BBC understands, but Archie and Lilibet will be referred to as prince and princess in formal contexts.
It is unclear whether the children have the right to use the HRH styling, as their father has not used it since leaving royal duties.
The rules for royal children’s titles were set by King George V in 1917.
As children of a sovereign son, Archie and Lilibet automatically have the right to be called prince and princess.
The Right Reverend John Harvey Taylor, the Bishop of Los Angeles, presided over the baptism. The former newspaper journalist worked in former US President Richard Nixon’s office between 1984 and 1990 before being ordained.
The BBC understands that some potential guests are being asked to save the date ahead of official invitations to be sent later.
Buckingham Palace has declined to comment on the guest list.