Justin Welby, the Archbishop of Canterbury, is to baptise Meghan Markle ahead of her marriage to Prince Harry.
The Suits actress actress, 36, will convert to Anglicanism in a private service overseen by the archbishop at a Kensington Palace chapel later this month.
Mr Welby will also conduct the marriage ceremony at Windsor Castle in May.
Ms Markle, who grew up in America, attended a Roman Catholic school. Her conversion to the Church of England is understood to be out of respect to Queen Elizabeth, who is its head.
Precise details of the baptism have not been revealed for security reasons.
The royal wedding will take place at Windsor’s St George’s Chapel on FA Cup Final day, May 19.
It starts at noon and at 1pm the couple will process in horse-drawn carriages around Windsor.
Kensington Palace said: “They hope this short journey will provide an opportunity for more people to come together around Windsor and to enjoy the atmosphere of this special day.”
Festivities are likely to have died down by the time the football kicks off at 5.30pm.