The Duke and Duchess of Sussex are to split from the charity they shared with the Duke and Duchess of Cambridge to set up their own foundation.
Prince Harry and Meghan will break away from the Royal Foundation and hope to establish a new charity by the end of the year, according to royal aides.
The couples will continue to work together on initiatives such as the Heads Together mental health campaign.
The foundation said the royals were "incredibly proud" of their joint work.
Set up in 2009, the Royal Foundation focused on causes close to the princes' hearts, including the armed forces, conservation and mental health.
In a statement, the charity - which will be renamed the Royal Foundation of the Duke and Duchess of Cambridge - said the decision was made after a review of its structure.
Image captionThe four royals held the first - and so far only - Royal Foundation forum together in London in 2018
"These changes are designed to best complement the work and responsibilities of Their Royal Highnesses as they prepare for their future roles, and to better align their charitable activity with their new households," it added.
"The Duke and Duchess of Cambridge and The Duke and Duchess of Sussex are incredibly proud of what they have achieved together through the Royal Foundation," it said.
Catherine joined after she became Duchess of Cambridge in 2011 and Meghan joined shortly before she and Harry were married in May 2018.
The couples took to the stage together at the charity's first forum in London in February 2018. The charity's title was later officially changed to The Royal Foundation of The Duke and Duchess of Cambridge and The Duke and Duchess of Sussex.
The move by the Sussexes is seen as the final step in the division of the couples' public duties.
Image captionThe royal charity said the dukes and duchesses were "incredibly proud" of the work they have done together
Image captionThe Heads Together campaign was launched in 2016 by the Duke and Duchess of Cambridge and Prince Harry to end the stigma around mental health
Earlier this year the duke and duchess split from the household of Kensington Palace, where William and Kate live with their children.
Prince Harry and Meghan appointed a separate head of communications and set up their own Instagram account.
They also moved to Frogmore Cottage, Windsor, in April - shortly before Meghan gave birth to their son Archie.