Now nearly six years on, Grace Van Cutsem is eight years old... and no longer grumpy!
Many would remember as the crowds cheered during William and Kate's first kiss on the balcony, the little cutie opted to maintain a rather ferrous, unimpressed scowl.
Just three at the time, the formalities proved too much for the tot.
Prince William's goddaughter has grown up quite a bit since, and has become a big sister once again.
Mum Rose and dad Hugh were already parents to Grace and a younger boy named Rafe, before they welcomed baby Charles a few months after the 2011 royal nuptials.
In fact, in the years since Grace became an Internet sensation, she's grown up quite a bit, with her mum Rose documenting her life on Instagram.
From being a school kid, to a big sister and even an avid hunter, it seems like Grace has become quite the well-rounded young lady... She's even been a flower girl for ten other weddings.
We're guessing there were no loud RAF flyovers...
Lady Louise Windsor was also one of the stars from the bridal party.
The flower girl is now 13 and just this week attended the Easter Sunday Service in Windsor with her grandmother, The Queen.
The daughter of Prince Edward and Sophie Countess of Wessex is the elder sister to little nine-year-old James, Viscount Severn.