The Duchess stunned in the pretty ensemble, with a clashing red bag, which appeared to be from British brand Mulberry.
The looks was reminiscent of the look she wore to Meghan Markle and Prince Harry’s christening for baby Archie.
The pink dress had a white print, and was matched with beige raffia wedges.
On her head were perched a pair of black sunglasses.
She was wearing the Ballon Bleu de Cartier watch, which costs upwards of £5,650.
This item was a gift from Prince William, who reportedly has a sapphire put in it to match Kate’s engagement ring.
Kate’s shoes are her well loved Castaner Carina 80 canvas wedge espadrilles, £80.
Meghan on the other hand wore a khaki top. She also wore a pair of gold sunglasses.
Her dark hair was loose and she kissed baby Archie Harrison tenderly on the head.
This is the first family outing for the royals for quite some time.
It is also is a rare glimpse of Louis, who has been missing from a number of public royal events recently.
Today he looked adorable in a green shorts, a navy polo stop and navy shoes.
Kate Middleton wore a fairly similar look at the recent christening of Archie.
At the time her look was praised by fans, who gushed over her headband and dress.
The gown was Stella McCartney and had a pussy bow tie neckline.
Users were quick to single out Kate’s stylish look, and one put: “Catherine stunning as always.”
A second added: “Kate looks so Elegant as always.”
A third continued: “Kate looks amazing,” before one agreed, and replied: “She does, she has really hit her stride.”
One then rounded off: “Lovely pic … great to see one of the family. Kate looks amazing, every inch our future Queen.”