The Duchess of Cambridge, who is patron of the iconic London museum, will attend a reception followed by a lavish gala dinner. Other famous faces who are set to attend include David Bailey, Olympic Gold medallist Katherine Grainger, Grayson Perry and Jonathan Yeo.
Kate will meet a selection of guests at the reception and take time to view some of the outstanding Pen Portraits and Mystery Portrait Postcards on display. Funds raised on the evening will go to the National Portrait Gallery.
The last time Kate visited the museum was in April 2013 when she was six months pregnant. The elegant royal, who wore a baby blue Emilia Wickstead cocktail dress that showed off her growing baby bump, was attending an event in honour of charity The Art Room.
As patron of the charity, Kate delivered an inspirational speech to the 250-strong audience. The Duchess said it felt "incredibly special" to be celebrating the organisation's work, which uses painting and drawing to build confidence and independence in young people.
"I am a firm believer in the power of art to make a difference, and The Art Room is providing this on a daily basis," said Kate.
The National Portrait Gallery holds a special place in Kate's heart. Her most famous visit was perhaps at the unveiling of her first official painted portrait in January 2013. Painted by award-winning artist Paul Emsley, the artwork initially received some criticism from the press, but Kate was herself delighted with the result, calling it "brilliant, amazing, absolutely brilliant".
Kate's picture has become the best-selling postcard in the National Portrait Gallery's shop, selling more than 3,000 reproductions in the first few weeks since the unveiling.