During the ceremony, she was gifted posies by the daughters of Warrant Office Second Class Alistair Wigley - six-year-old Aoife and four-year-old Alice whom she graciously thanked and told them that they looked “gorgeous”.
Kate was honoured by her husband during a speech he gave later in the day.
Speaking to the guardsmen, the heir to the throne said being their Colonel was “one of the great honours of my life”.
He continued, “I may be stepping aside, but in Colonel Catherine you have a committed, focused, and already incredibly loyal 11th Colonel.
“As you serve together over the years ahead, know that I will continue to watch you, with huge pride in having been one of you.”
It comes after the royal couple appeared at the BAFTAs last month and were caught in a rare public display of affection.
Much to the delight of fans, the Princess of Wales was caught giving Prince William and cheeky tap on the behind before they walked the red carpet.
William and Kate whispered to each other before the flirty exchange was captured on camera.
It was a rare moment of affection for the Prince and Princess of Wales, who appeared to be relaxed as they enjoyed attending the event and walking the red carpet together.