Kate Middleton has decided not to attend Royal Ascot at the last minute, sparking new worries about her health while she continues to recover from cancer.

The Princess of Wales, 43, was due to attend Wednesday’s prestigious race day alongside Prince William, King Charles and Queen Camilla.

However, Kensington Palace had published a revised attendance list at shortly after noon that did not include the princess. No reason was given.

Supporters and other attendees were eager to see the cherished royal, as she had been listed among the royals presenting race prizes.

She was slated to ride in the second Royal Procession carriage with her husband, the future king.

In light of her unexpected absence, the Prince of Wales, 42, will now accompany the monarch, 76, and his wife in the first carriage, with Prince Saud bin Khalid Al-Saud joining them.

The Post understands the Princess of Wales is disappointed to have to skip the event.

As the princess remains out of the public eye, her mother, Carole Middleton, attended the glitzy race event with her daughter-in-law, Alizee Thevenet.

Thevenet — who has been married to Princess Catherine’s brother, James Middleton, since 2021 — was pictured smiling with her mother-in-law as they watched all the sporting action.

The princess’ last-minute withdrawal from the event suggests she is carefully managing her public appearances after announcing that her cancer was in remission in January.

The mom of three has been making a gradual return to public-facing duties in recent months — and doing so with grace and poise.

In the past week alone, Middleton had attended three high-profile royal events.

She was seen in a striking turquoise ensemble at Saturday’s Trooping the Colour ceremony, during which she appeared on the balcony with her husband and their three children.

On Monday, she attended the annual Order of the Garter service, followed by a visit to a V&A East Storehouse, a branch of the Victoria and Albert Museum in London.

The king and queen, for their part, attended race day at the Royal Ascot on Tuesday where they rubbed elbows with Princess Anne’s son’s new flame.

Charles and Camilla, 77, hosted a handful of guests in their royal box on the first day of the races, which included Peter Phillips and his new partner, Harriet Sperling.