The Princess of Wales thanked the public for "all the wonderful messages of support" amid her recovery from major abdominal surgery, before revealing she is undergoing treatment for cancer.
Princess Kate described the news as a "huge shock" in a moving video shared to the Prince and Princess of Wales' official Instagram account, which has been viewed by more than 93 million people since it was shared on Friday.
Amongst royal fans wishing Princess Kate well amid her cancer diagnosis is Mila Sneddon, eight, who met Kate in 2021 when she was five years old, after her own cancer story touched the royal's heart.
The Sunday Mail reported Mila urged the princess: "You will be brave because I was and you will fight it like I did."
Mila, who is now in remission, was diagnosed with acute lymphoblastic leukaemia and underwent intensive chemotherapy treatment when she first came to the Princess of Wales' attention.
The then-six-year-old captured Kate's heart after a photograph of the little girl was included as part of the royal's Hold Still project in 2020.
Mila, who was undergoing chemotherapy for leukaemia at the time, was pictured kissing her home's kitchen window after being separated from her father during the first lockdown.
In what has become one of Princess Kate's most moving and memorable royal engagements, at Mila's request, the royal promised to wear pink the first time she met the little girl in person.
The royal chose to wear her bubblegum pink Me+Em dress when she invited Mila and her mother to Holyrood House. Mila’s mother Lynda, 40, said Kate’s announcement on Friday that she was undergoing a course of "preventative chemotherapy" had come on the two-year anniversary of Mila being in remission.
Lynda told the Sunday Mail: "Kate showed Mila such compassion, care and support both during and post treatment. So it’s been very emotional to see she is now facing her own health struggles."
"We have nothing but admiration for her to have been able to come out and publicly tell her story."
She revealed that Mila will be making and sending Kate a handwritten card, before adding: "Cancer is like a community and a club that no one wants to be in.
"We are very sad to hear she has joined the club but the Sneddons are completely behind her and we wish her the very best.