Getting all nostalgic, Becks reflected on the years he has had with his little girl since her arrival back in 2011, and to do so, he posted his favourite photo of himself and Harper for fans to see.
One word springs to mind... ADORABLE.
In his black and white throwback photo, David can be seen cradling little Harper when she was just a baby. The birthday girl can only be a few weeks old, months at most, as she lay on her daddy's chest.
Alongside his photo, David - who recently celebrated his anniversary with wife Victoria - gushed: "Possibly my favourite picture of Harper of all time... 4 beautiful years with the most amazing little girl... Happy birthday big girl."
We bet your hearts are melting, right?
David's birthday message to Harper comes after the former footballer boasted his daughter was following in his footsteps.
Following Victoria's admission that Harper was a "tomboy at heart", David posted a picture of Harper practicing her footballing skills in the garden.
Making reference to pro female soccer player Mia Hamm, David teased alongside his snap: "Mia Hamm eat your heart out. Harper Seven taking lessons from her brothers (oh and her dad)."
Not only does she have a pretty impressive set of coaches to hand to help her game (only the former Captain of England - no biggie!), she even has all the kit to make her look the part.
Receiving an early birthday present last month, David revealed Harper had been treated to her very own and personalised England kit.
Do we have the next female footballing pro on our hands? Maybe, watch this space...
For exclusive competitions and amazing prizes visit Reveal's Facebook page NOW!