HRH has a second official birthday as monarch which falls on the second Saturday of June thanks to an ancient royal tradition.
The practice started back in 1748 when King George II lamented the dismal weather he faced each year on his November birth date.
In true monarchical fashion, the King took matters into his own hands and solved the meteorological problem by combining his natural birthday with an annual military parade held every summer.
The official Instagram accounts of the Duke and Duchess of Cambridge and the Duke and Duchess of Sussex, both wished Her Majesty a happy birthday.
"Wishing a very happy 93rd birthday to Her Majesty The Queen!" wrote Prince William and Kate Middleton via their Kensington Royal Instagram account.
As for Meghan and Harry, the parents-to-be posted a series of sweet snaps of the pair with Queen Elizabeth to their Sussex Royal account, captioning the photo series: "Happy Birthday Your Majesty, Ma’am, Granny. Wishing you the most wonderful day! 🎈Harry & Meghan."
Queen Elizabeth, born Elizabeth Alexandra Mary on April 21 1926, is the world's longest reigning monarch.
The Queen won the accolade on September 9 2015 when she surpassed the reign of her great-great-grandmother, Queen Victoria.
Happy birthday, Your Majesty!
WATCH! A Young Princess Elizabeth II riding around Sandringham in the early 1940s!