During the visit, he attended a series of charity events and also reunited with King Charles for the first time in 19 months.
The Telegraph reported the female stalker entered a "secure zone" at a London hotel where Harry attended a WellChild awards ceremony.
The newspaper also revealed that two days later, the woman was spotted "a stone's throw" from the Duke of Sussex when he visited Imperial College London's Centre for Blast Injury Studies.
It was reported that a member of Harry's private security staff "body-blocked" the woman to prevent her from getting any closer.
The woman has been identified as a "fixated individual" by Harry's personal protection team and has a history of following the Duke and Duchess of Sussex, the newspaper said.
She was even spotted in Nigeria during the couple's visit in 2024.
Harry, 41, and Meghan, 44, announced they were stepping back as working members of the British royal family in January 2020.
Following their departure from the royal family, the couple were told that they would not be able to retain the full-time police protection granted to the royals.
The Sussexes would instead receive a "bespoke" security service, whereby they would be required to give 30 days' notice of any plans to travel to the UK, with each visit being assessed for threat levels and whether protection is needed.
In May, Harry lost his Court of Appeal challenge over his security arrangements while in the UK and said, in the TV interview following the decision, he "can't see a world in which I would be bringing my wife and children back to the UK".
On Saturday, Meghan attended the Balenciaga show at Paris Fashion Week in support of her friend, the fashion designer Pierpaolo Piccioli.
