From a giant "HAPPY BIRTHDAY HART" balloon display, to an incredible and colourful train ride for party-goers, Miranda went all out.
"Happy 1st Birthday my little angel Hart," Miranda captioned a photo of gold balloons floating in the sky, in celebration of her and billionaire hubby Evan Spiegel's son.
The Aussie supermodel - who's pregnant with her third child, second with Evan - also treated her Instagram followers to Hart's very first birthday cake - and it was sooo cute!
He must be a fan of lions, tigers, giraffes, elephants and bunnies!
Some of the Kora mogul's celebrity friends got in on the action, with Jesinta Campbell commenting with three love heart emojis, while model Lily Aldridge wrote, "Sweeeeetest!" and "Happy Birthday Hart."