Kate, who last March announced she was undergoing treatment for cancer, posted the message online alongside a short video featuring shots of her and Prince William in Norfolk last summer.
The clip also showcases some of the UK’s most striking natural environments – from woodlands and fields to the coastline and the ocean.
In the message, signed “C”, the 43-year-old princess wrote: “Over the past year, nature has been our sanctuary.
“This Mother’s Day, let us celebrate Mother Nature and recognise how our bond with the natural world can help not only nurture our inner selves, but remind us too of the role we play within the rich tapestry of life.”
The princess underwent a course of preventative chemotherapy following her cancer diagnosis.
In January, she praised the “exceptional” care she had received at The Royal Marsden as she revealed she was in remission.
The King, 76, was also diagnosed with cancer last year and spent a “short period of observation in hospital” on Thursday after experiencing side effects from his treatment.
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The Royal Family’s official X account also shared two pictures online in celebration of Mother’s Day.
One image shows a young Prince Charles and Princess Anne attending the Royal Windsor Horse Show with the late Queen Elizabeth in 1956.
The second picture shows Queen Camilla’s late mother Rosalind with her eldest grandson, Tom Parker Bowles.
The post read: “Wishing all mothers, and those who are missing theirs today, a peaceful Mothering Sunday.”
