The Duke and Duchess of Sussex sent well-wishes to William, Harry's elder brother and the Duke of Cambridge, on his 37th birthday Friday.
Kensington Palace shared a photo of William smiling during a visit to Kenya, writing, "Thank you everyone for your lovely wishes on The Duke of Cambridge's birthday!" Harry and Markle replied in the comments.
"Happy Birthday to the Duke of Cambridge!" the couple wrote from their official @SussexRoyal account.
William and Harry's father, Charles, Prince of Wales, shared a throwback photo and well-wishes on the Clarence House official Twitter account.
"Happy Birthday to HRH The Duke of Cambridge, who turns 37 today. #HappyBirthdayHRH," the post reads. "The Prince of Wales and Prince William play in the garden at Kensington Palace, 1984."
Kensington Palace announced in a statement Thursday Harry and Markle have split from The Royal Foundation, the joint charity they shared with William and his wife, Kate Middleton. Harry and Markle will establish their own charitable foundation.
"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.
"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 palace added. "In addition both couples will continue to work together on projects in the future, including on The Foundation's mental health program, Heads Together."
Harry and Markle and William and Middleton split their royal household in March ahead of the birth of Harry and Markle's first child, Prince Archie. Harry and Markle shared a new photo of Archie on Father's Day this week.