The couple encouraged their supporters to donate to provide COVID-19 vaccinations to people in underserved countries.
The Duke and Duchess of Sussex shared a sepia-toned image of Archie standing with his back to the camera on the Archewell Foundation's website for the special occasion. In the cute photo, their son is holding a bunch of balloons and looking up at them. ET can confirm it is Archie in the photo.
The couple, who recently served as co-chairs for Global Citizen's VAX LIVE: The Concert to Reunite the World, also shared an update on their Archewell Foundation's website on Thursday.
"Join Us in Advocating for Vaccine Equity on Archie's Birthday," the Duke and Duchess of Sussex titled the post.
Noting that many members of the public have donated to charities on their son's behalf in the past, the couple requested that this year's donations be focused on helping to provide COVID-19 vaccinations to people in underserved countries.
"While some places are on the verge of healing, in so many parts of the world, communities continue to suffer," the couple shared. "We will not be able to truly recover until everyone, everywhere, has equal access to the vaccine. And with that intention, we are inviting you to contribute whatever you can — if you have the means to do so — to bring vaccines to families in the world’s most vulnerable places."
They added that by donating $5, you can cover the cost of a vaccine dose for a person in need. They've also partnered with other organizations willing to match donations, automatically turning $5 into $20.
"We cannot think of a more resonant way to honor our son’s birthday," the duke and duchess concluded the post. "If we all show up, with compassion for those we both know and don’t know, we can have a profound impact. Even a small contribution can have a ripple effect."
The couple are currently expecting their second child, a baby girl, this summer. They have mostly kept Archie out of the public eye since announcing their decision to step down as senior members of the royal family in 2020.
Archie also received some love from his family across the pond on Thursday with his great-grandmother Queen Elizabeth II, grandfather Prince Charles, and uncle and aunt Prince William and Kate Middleton all sharing posts in honor of his special day.
As for how Harry and Meghan are celebrating Archie's birthday, royal expert Katie Nicholl tells ET that they're remaining tightlipped about their plans, but despite the royals' issues with one another, they always planned on celebrating.
"I understand that there were plans for a Zoom call. I know the Queen is particularly keen to see Archie today because of course none of the family has seen him for about 18 months now," Nicholl notes. "They are missing out on all those important milestones. I do know that when it comes to birthdays, great efforts have been made, particularly with the Sussexes in Los Angeles, for there to be some kind of connection with the family. Just an opportunity to say hi, happy birthday."
Nicholl says if there is a party for Archie, it will be "lowkey."
"A small birthday party at the family home. I would imagine that Meghan's mother, Doria [Ragland], will be there, but I think they will keep it pretty tightknit," she shares. "I think if you look at his birthday party last year, it was pretty lowkey. I can see Meghan probably making a cake, it being a time for the family to come together and to mark this second birthday."