Princess Lilibet Diana, who turns two in June, was christened at the couple’s LA home last week.
The Duke and Duchess of Sussex’s daughter has been christened at the couple’s California home.
Princess Lilibet Diana, who was born to Prince Harry and Meghan in June 2021, was christened 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 spokesperson said members of the Royal Family were invited to the christening.
Although she was not a princess at birth, because she was not a granddaughter of the monarch, she gained the right to that title when King Charles acceded to the throne.
Buckingham Palace has said the royal website – which currently lists her and brother Archie with the titles miss and master – will “be updated in due course” to reflect the title.
Lilibet is the second child of Harry and Meghan, who relocated 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 were in attendance.
Harry and Meghan are understood to want their children to decide for themselves whether or not to use their titles when they are older.
The couple will not use the titles conversationally, the BBC understands, but Archie and Lilibet will be referred to as prince and princess in formal contexts.
It is unclear if the children are entitled to use the HRH styling given that their father has not used it since quitting royal duties.
The rules governing the titles of royal children were set out by King George V in 1917.
As the children of the son of a sovereign, Archie and Lilibet are automatically entitled to be called prince and princess.
Right Reverend John Harvey Taylor, the Bishop of Los Angeles, presided over the christening. The ex-newspaper journalist worked in the office of former US President Richard Nixon between 1984 and 1990 prior to being ordained.
Earlier this week, it emerged that Harry and Meghan were weighing up whether or not to travel to the UK for the King and Queen Consort’s coronation.
A statement issued on behalf of the couple said Harry had been contacted about the event on 6 May by the King’s private office via email.
The BBC understands some prospective 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.