The royal brothers will attend a British Summer themed party at BGC partners in London's Canary Wharf before moving to the brokerage company's trading floor to assist employees with telephone deals.
The revenues from the day's trade will go to a number of charities including SkillForce, of which William is a Patron, and WellChild, of which Harry is a Patron.
The charity day is an annual event to remember the 658 company employees who lost their lives on 11 September 2001.
Later in the day, new uncle Prince Harry will attend the annual WellChild Awards at The Dorchester Hotel on Park Lane. In 2007, Harry became a Patron of the UK children's charity which is committed to ensuring that sick children have the very best possible quality of care.
The 28-year-old, who is often praised for his innate ability to connect with children, will present the award for 'Most Inspirational Child' aged three to six and deliver a speech at the end of the ceremony.
The fun-loving royal will be joined by a number of WellChild supporters in recognising the courage of seriously ill children and young people as well as the hard work of the doctors and nurses who care for them.
The winners of each category and members of their families will get the chance to meet the fourth in line to the throne at a reception before the ceremony.
The following day, 31-year-old William will be supporting another charity, this time with his wife Kate Middleton by his side.
It will be the new mum's first public appearance since giving birth to Prince George in July.
The Duke and Duchess of Cambridge will be guests of honour at the inaugural Tusk Conservation Awards.
After winning fashion fans worldwide with her impeccable maternity wardrobe, Kate's style watchers will no doubt eagerly await the outfit she chooses for the event.
As it's their first public appearance as parents, William, his wife and their baby boy will undoubtedly be the talk of the evening. At the heart of the occasion, however, is the honouring of unsung heroes of wildlife conservation.