The Princess of Wales returned to work on Tuesday for the first time following the completion of her chemotherapy treatment.
Kate attended an Early Years meeting with a group at Windsor Castle, according to the Court Circular published on Tuesday evening.
It is only the third time she has been mentioned in the official record of engagements noted in the circular since the princess began her cancer journey earlier this year.
She attended with members of her household team but without the Prince of Wales, who had a separate engagement.
The princess’s major public project is supporting the early years development of children.
Last year she launched her long-term campaign Shaping Us, described as her “life’s work” and aimed at highlighting the crucial first five years of a child’s life.
Kate, who is continuing to work from home, is hoping to return to a light programme of public duties in the coming months.
She is also working towards appearing with the royal family at the annual Remembrance Sunday service staged at the Cenotaph in Whitehall.
Her Christmas Carol concert at Westminster Abbey has become a firm fixture in recent years and she has begun working with her team on the project and is likely to host the event.
Earlier this month, Kate appeared in a deeply personal video with her family - husband William, sons Prince George and Prince Louis, and daughter Princess Charlotte - to confirm the end of her preventive chemotherapy course but said her focus was staying “cancer-free”.
Spoken over images showing the Waleses and their children enjoying the outdoors near their Norfolk home, they are seen walking through woods. The Prince and Princess of Wales cuddle as they hold hands.
She describes the past nine months since her serious health issues began as “incredibly tough for us as a family” and how the “cancer journey is complex, scary and unpredictable for everyone”, with the experience giving her a “new perspective on everything.”
In the video, Kate says: “Doing what I can to stay cancer-free is now my focus. Although I have finished chemotherapy, my path to healing and full recovery is long and I must continue to take each day as it comes.
“I am however looking forward to being back at work and undertaking a few more public engagements in the coming months when I can.
“Despite all that has gone before, I enter this new phase of recovery with a renewed sense of hope and appreciation of life.”
The princess had been receiving chemotherapy for an undisclosed form of cancer since late February with King Charles beginning his care earlier that month following his cancer diagnosis after treatment for an enlarged prostate.
The princess was initially admitted to hospital for abdominal surgery on January 16 and at the time, her condition was thought to be non-cancerous but tests after the successful operation found cancer.
She appeared emotional in a video in March where she announced the state of her health and spoke of the “huge shock” of the medical development.
While receiving treatment, Kate had been undertaking some work behind the scenes and attended the King’s birthday parade, also known as Trooping the Colour, in June. The following month, she presented the winning trophy in the men’s Wimbledon final to Carlos Alcaraz, with both events featured in the Court Circular.
The Prince of Wales was also named in the official record for Tuesday, after he visited 22 Special Air Service Regiment in Credenhill, Herefordshire.
