Lorraine Heggessey is to step down as chief executive of the Royal Foundation this autumn.
Heggessey, a former controller of BBC One, had been at the charity for two-and-a-half years and will be replaced by Jason Knauf in October.
Knauf is senior adviser to the Duke and Duchess of Cambridge at Kensington Palace and previously led their communications team for four years.
The foundation was the charitable vehicle for both the Duke and Duchess of Cambridge and the Duke and Duchess of Sussex.
However, last month it was announced that the Duke and Duchess of Sussex would break away from the foundation to create their own charity.
The charity’s latest financial accounts show it had a total income of £7.8m and spent £9m in 2018.
During her time in charge, Heggessey is credited with overseeing the expansion of the foundation’s Heads Together mental health programmes and providing financial support to Shout, a digital mental health service.
The foundation also provided funding for the Together cookbook, which helped raise money for communities affected by the Grenfell Tower fire.
The Duke and Duchess of Cambridge said: "Lorraine has played an integral role in our charitable initiatives over the last two-and-a-half years. We are very grateful for her hard work and support, and wish her the very best for the future.
"We are pleased that Jason has been appointed as chief executive and very much look forward to working with him in his new role."
The Duke and Duchess of Sussex said: "It has been a great pleasure to work alongside Lorraine over the past couple of years to champion the causes that we feel so strongly about, and we wish her well for the next stage of her career.
"We have had an extremely positive working relationship and we are enormously grateful for her personal and professional support."
Heggessey said it had been an honour to work with their royal highnesses but it was the right time to step down. She now plans to pursue interests in the media.