Catherine, Princess of Wales, announced on Tuesday that she is "in remission" from cancer after she and Prince William visited the specialist London hospital where she received treatment.
"It is a relief to now be in remission and I remain focussed on recovery," the princess posted on Instagram, alongside a picture of her visit to the Royal Marsden Hospital.
The couple thanked staff and met patients at the specialist cancer center operating across three sites in the capital.
"I wanted to take the opportunity to say thank you to The Royal Marsden for looking after me so well during the past year," Catherine wrote on Instagram.
"My heartfelt thanks goes to all those who have quietly walked alongside William and me as we have navigated everything.
"We couldn't have asked for more. The care and advice we have received throughout my time as a patient has been exceptional," she added.
The visit came as Kensington Palace announced that the couple had become the hospital's joint patrons.
As patrons, members of the royal family support over 3,000 organizations such as charities and hospitals by highlighting their work through visits.
"In my new role as joint patron of The Royal Marsden, my hope is that by supporting groundbreaking research and clinical excellence, as well as promoting patient and family wellbeing, we might save many more lives, and transform the experience of all those impacted by cancer," said the princess.
The visit was said to be "incredibly poignant" for the princess, also known as Kate, who turned 43 last week.
The future queen, whose popularity is seen as key to maintaining the royals' position in a changing Britain, revealed last March she had been diagnosed with an unspecified cancer and was undergoing chemotherapy.
"The princess wanted to make the journey to both show her gratitude to the incredible team, but also highlight the world-leading care and treatment the Marsden provides," a Kensington Palace spokesperson said.
It is the first time the royal family has given any information about where Catherine was treated.
She announced in September that she had completed a course of chemotherapy and was doing her best to remain "cancer-free."
She reflected on her diagnosis in a video message at the same time that showed her relaxing in the countryside with William, who is heir to the throne, and her three children Prince George 11, Princess Charlotte, nine, and six-year-old Prince Louis.
"Life as you know it can change in an instant and we have had to find a way to navigate the stormy waters and road unknown," she said, adding the previous nine months had been "incredibly tough."
She wrote on Tuesday that "as anyone who has experienced a cancer diagnosis will know, it takes time to adjust to a new normal."
"I am however looking forward to a fulfilling year ahead. There is much to look forward to."
Catherine's diagnosis came just weeks after the U.K.'s head of state King Charles III revealed he too was receiving treatment for cancer.
Both have since made a return to public life, although Catherine's has been more limited.
The Royal Marsden opened its doors in 1851 as the world's first hospital dedicated to cancer treatment and research.
