The Princess of Wales' return to public life following her cancer diagnosis came at one of the highlights of the royal calendar - Trooping the Colour.
It was only revealed just hours before the King's Birthday Parade that Kate, 42, would be participating in the day and royal fans were delighted to see her take part in the carriage rides with her children Prince George, Princess Charlotte and Prince Louis as well as greet the crowds from the Buckingham Palace balcony.
Before Saturday, many had wondered how Kate would make her first appearance since her emotional video back in March, where she delivered her cancer news and revealed her chemotherapy treatment.
And according to the Daily Mail, Kate chose to return at Trooping the Colour because of her three children and father-in-law King Charles, who is also having cancer treatment.
Its royal editor Rebecca English writes: "In order for the youngsters to be there and play a full role - riding in a carriage on The Mall, watching proceedings on Horse Guards and joining the family 'balcony moment' - Mummy needed to be there too to keep the 'kiddies' (as she calls her young brood) in check as Papa [Prince William] was on horseback.
"For Kate, there was also a determination to support the father-in-law she has become increasingly close to over the years and with whom she now shares the unenviable bond of a serious health battle. "
It comes as Kate said in a statement on Friday she was making "good progress" with her treatment but candidly added she has "good days and bad days" and, although she has been working from home, said, "I am not out of the woods yet". Support from the public has made a deep impression on the princess, who said she had been "blown away" by the "kind messages" that had made a " world of difference to William and me and has helped us both through some of the harder times".
At Trooping on Saturday and in change from last year, Kate did not join senior family members on a dais to watch the ceremony on Horse Guards Parade but watched the event from the Duke of Wellington's former office with her children. During the military spectacle, Louis was seen yawning as he viewed the ceremony from the historic building overlooking the parade ground, and later the young royal danced during the quick march of the Scots Guards to Highland Laddie.
Later she joined the rest of the Royal Family on the Buckingham Palace balcony for the thrilling RAF flypast. During the aerial show, William was pictured affectionately pulling Louis' ears as Kate watched and grinned and when the national anthem was played, big sister Charlotte gave her younger sibling a nudge to stand still.
Kate is not expected to return to full-time royal duties until she has fully recovered. Royal sources said public duties would be measured with how she feels at any given time and would not include today's Order of the Garter ceremony or any part of the Royal Ascot festival, which begins tomorrow.
Prior to her announcement that she would be at Trooping, royal sources confirmed the princess had personally spoken to the King and informed him of her wish to join him and the royal family for the parade. A spokesperson for the King said His Majesty was "delighted" by the news of her attendance.