The Duchess of Cambridge, 34, was at the landmark gallery to take a look at the Vogue 100: A Century of Style exhibition, featuring the cover photographs she recently shot for the magazine.
Wearing a gorgeous peach dress, made by designer Alexander McQueen, Kate looked every inch the perfect princess as she posed for waiting photographers outside.
The mum-of-two's wool frock flattered her slim figure thanks to a peplum skirt and it fell just below her knees. Kate coordinated it with a matching clutch bag, nude heels and wore her hair in her trademark blow-dry.
On her arrival, Kate was met by the gallery's director Nicholas Cullinan and British Vogue editor Alexandra Shulman. It is the first time she has seen the pictures, which will feature as part of a wider spread in the glossy magazine's centenary edition, out in June.
The event marks the end of a busy day for Kate, who attended the opening of a new children's playground at Hampton Court Palace this morning.
While at the event, she revealed that Prince George and Princess Charlotte have a pet hamster called Marvin!
Kate later attended a luncheon at the Anna Freud Centre in London. The Duchess is a patron for the centre, which helps children and young adults with mental health problems.