Wearing a floor-length ink blue by Jenny Packham, she turned heads as guest of honour at the 100 Women Hedge Funds Gala to benefit one of the charities close to her heart, Action on Addiction.
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The sophisticated v-neck, short-sleeved dress is from the British designer's Autumn/Winter 2013 collection. The silk tulle number featured a discreet velvet belt.
The 31-year-old was a guest of honour at the 100 Women Hedge Funds Gala to raise funds for one of the charities close to her heart, Action on Addiction.
Arriving at the event, she spoke about George's exemplary behaviour on his big day, "He's such a good boy actually, we're very lucky, he's not always like that."
Held in the magnificent Kensington Palace State Apartments, Kate didn't have to travel far from her baby son Prince George and husband Prince William for the event.
The young family moved into the London palace's refurbished Apartment 1A at the beginning of October.
Mingling with some of the most powerful women in business, the Duchess of Cambridge attended the reception and was due to present Dame Amelia Fawcett, DBE with the coveted European Industry Leadership Award during dinner.
There will be some familiar faces in the crowd too — the popular royal attended the same dinner in 2011 alongside her husband, where she wowed invitees in a striking red gown.
Kate is there in her capacity as patron of Action on Addiction, the UK-based charity which works to provide treatment, education and support for those affected by addiction. The charity is part of The Charities Forum of the Duke and Duchess of Cambridge and Prince Harry.
The new mum is no doubt keen to raise as much money as possible at the glamorous event, and guests are reportedly paying up to £60,000 a table for the best views. The brunette beauty began a three-year patronage for 100 Women in Hedge Funds on 1 January 2013.
Earlier this year the Duchess gave a rare speech at a Manchester primary school on the issue of addiction which she described as a "hugely complex and destructive disease."
The new mum has been easing her way back into the public eye since giving birth on 22 July. Last week she attended her first solo engagement as a mum at a SportsAid charity event at London's Olympic Park where she made headlines for athletic prowess as she joined in a game of volleyball.