Fresh from her luxury holiday to The Maldives, the mother-of-one, 31, looked beautiful in a fitted emerald green Hobbs coat and matching Gina Foster hat. She also wore green heels.
She was at the annual parade alongside husband Prince William, who was acting as Colonel of the Regiment, to hand sprigs of shamrock to the officers and guardsmen.
The Irish Wolfhound also got a sprig. He's the very handsome mascot of the 1st Battalion The Irish Guards.
Thankfully, there was no heel mishap this year after Kate famously got her shoe stuck in the drain while attending last year's event.
Kate looked refreshed and tanned following her sunshine break abroad, which came just a couple of months after a family holiday to the Caribbean island of Mustique. Lucky for some!
This time last year, Kate was handing out sprigs of shamrock while pregnant with her first child, Prince George. The baby, born in July 2013, wasn't in attendance at today's event.
Since his birth, the third-in-line to the throne has been kept largely away from the cameras - the last time we caught a glimpse of Prince George was his Christening back in October.
It's expected we'll be seeing some more of him next month, however, when he joins Kate and William on their three-week official tour of Australia and New Zealand. They'll arrive in Australia on 7 April.
"The Duchess has never visited either country, so this is a chance for her to meet the people of New Zealand and Australia for the first time," said the couple's private secretary. "The Duke last visited New Zealand in March 2011, shortly after the devastating earthquake in Christchurch. During the same visit, he also went to Victoria and Queensland in Australia, which had been very badly affected by natural disasters.
"So, for the couple, this visit represents a wonderful opportunity on the one hand for The Duke to deepen his personal relationship with, and admiration for, New Zealand and Australia; and on the other, for the Duchess to experience some of the extraordinary warmth and hospitality for which the people of both countries are renowned the world over."
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