Kate Middleton First Public Appearance Since Cancer Announcement

Kate Middleton just made her much-anticipated return to the spotlight after her cancer diagnosis earlier this year -- and, as expected, the eyes of the world were watching her every move.

The Princess of Wales announced Friday that she would attend Saturday's Trooping the Colour Ceremony in London -- and she didn't disappoint and appeared as elegant as ever.

Check out the photos ... Kate was chauffeured to the event with her hubby, Prince William, and their two sons, Prince George and Prince Louis, along with their daughter Princess Charlotte. Kate was decked out in a classy white dress and a wide brimmed hat with some pricey jewelry.

Earlier, the royal family piled into the car at Buckingham Palace before they were filmed departing for the annual ceremony, which celebrates the British monarch’s official birthday.

There was another special treat, too. King Charles, who was also diagnosed with cancer, swung by to enjoy all the pageantry with Kate and the fam.

It was nice to see Charles and Kate feeling strong enough to go out and do things, which is always a good sign.

What's more ... Kate provided an update Friday on her cancer treatments, while posting a photo of herself on Instagram, where she was seen casually leaning back against a tree.

Kate wrote that she was "making good progress, but as anyone going through chemotherapy will know, there are good days and bad days." She added that her treatments will continue for several more months. She also acknowledged she's not out of the woods.

In March ... Kate first revealed that she had cancer in an emotional video message released publicly.

Sources with direct knowledge have told TMZ ... Kate's treatments have gone well over the last 3 months, leading up to today's outing.