The mother-of-four then took to Instagram Stories to share an inside look at the private party, showing her backyard transformed with rainbow colours, blow up castles, lollipops and a Mr Whippy - or Softy, as its named in the US - truck.
For the day, birthday girls North and Penelope wore matching, colourful, lolly covered outfits with North going as far as to wear fake rainbow braids in her hair:
While we search our room for anything rainbow covered to wear today, take a look inside the party to end all parties below.
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This article originally appeared on InStyle Australia