The future king turned 37 on June 21.
Instead of posting a tribute on their own Instagram page, the Duke and Duchess of Sussex wrote in the comments section of Kensington Palace’s Instagram which featured a special message from the Duke of Cambridge.
"Thank you everyone for your lovely wishes on The Duke of Cambridge's birthday!" Kensington Palace wrote.
“Happy Birthday to The Duke of Cambridge!” said Prince Harry and Duchess Meghan's message. This comes one day after it was announced that the Duke and Duchess of Sussex have formally split from Prince William and Kate Middleton's charity, The Royal Foundation, in order to start their own.
"The Royal Foundation of the Duke and Duchess of Cambridge and the Duke and Duchess of Sussex has today announced the conclusions of a review into its structure, and how it will best support Their Royal Highnesses with future charitable activity,” the palace said in a statement on Thursday. “Later this year, The Royal Foundation will become the principal charitable and philanthropic vehicle for the Duke and Duchess of Cambridge. The Duke and Duchess of Sussex will establish their own new charitable foundation with transitional operating support from The Royal Foundation.”
The two couples will still work together on some future projects such as The Royal Foundation’s mental health charity, Heads Together.
Meanwhile, the Royal Family's official Instagram handle posted an extensive post for Prince William.
"Happy Birthday to The Duke of Cambridge!" it stated. "The Duke of Cambridge is second in line to the throne. His Royal Highness undertakes a number of charitable activities and projects, and carries out public and official duties in support of The Queen, in the UK and overseas, alongside The Duchess of Cambridge."