The 31-year-old is the guest of honour at the 100 Women in Hedge Funds Gala to benefit Action on Addiction.
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It will held in the glamourous surroundings of the Kensington Palace State Apartments – meaning Kate won't have far to travel.
She moved into the palace's Apartment 1A with baby George and Prince William at the start of October.
The Duchess will attend a reception for selected guests, and during dinner will present Dame Amelia Fawcett, DBE with the coveted European Industry Leadership Award.
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 Duchess will no doubt be keen to raise as much money as possible for the glamorous event, and guests are reportedly paying up to £60,000 a table for the best views. Kate attended the same dinner in 2011 alongside her husband, where she turned heads in a striking red gown.