"Wishing Archie a very happy first birthday today!" William and Kate's official Kensington Palace Instagram account captioned the photo.
The official royal family also posted a touching photo of Queen Elizabeth smiling down upon her eighth great-grandchild after his birth. The queen is joined by her husband, Prince Philip, Harry and Meghan as well as Meghan's mom, Doria Ragland.
"Happy Birthday to Archie Mountbatten-Windsor who is celebrating his 1st birthday today!" the royal family's official Instagram account captioned the sweet pic.
Prince Charles' office, the Clarence House, followed suit with a black and white photo showing three generations--the Prince of Wales, son Harry, and Archie in his christening gown.
"A very Happy Birthday to Archie, who turns one today. This photo of Archie and his grandfather was taken following his christening in July 2019," reads the caption.
Prince Harry and Meghan welcomed Archie into the world at 5:26 a.m on May 6th, 2019. The Duke and Duchess of Sussex announced the news via their former joint Instagram account, Sussex Royal.
"We are pleased to announce that Their Royal Highnesses The Duke and Duchess of Sussex welcomed their firstborn child in the early morning on May 6th, 2019. Their Royal Highnesses’ son weighs 7lbs. 3oz.," the couple announced.
"The Duchess and baby are both healthy and well, and the couple thank members of the public for their shared excitement and support during this very special time in their lives. More details will be shared in the forthcoming days," the statement said.
Archie is seventh in line for the British throne. Harry is the younger son of Prince Charles, the next in line to the throne, and the late Princess Diana.
Outside of Windsor Castle on the family's special day, Harry told reporters that Meghan and Archie, who had yet to be named, were doing well.
"I'm very excited to announce that Meghan and myself had a baby boy early this morning, a very healthy boy," the new dad shared. "Mother and baby are doing incredibly well. It's been the most amazing experience I could ever possibly imagine. How any woman does what they do is beyond comprehension but we're both absolutely thrilled and so grateful to all the lovely support."
Meghan and Harry kept their plans for Archie's arrival private in the months leading up to his delivery. The couple did not disclose the location they chose for the birth and throughout Meghan's pregnancy, they never revealed his due date. They previously mentioned they did not find out the sex in advance.
Archie's first birthday is certainly marked with some firsts for the Duke and Duchess of Sussex. In addition to celebrating the life of their first child, Archie's birthday falls during the unprecedented time of the coronavirus crisis and just a couple of months after they relocated from Vancouver, Canada to Los Angeles, Calif following their departure as senior members of the royal family.
In March, Meghan shared an update about the couple's then-10-month-old, telling a crowd at a royal event that baby Archie was "into everything."