Keeping Up With The Kardashians star Kim has revealed the unfortunate accident happened while the family were being shot while lounging on a sofa.
Little North, born June 2013, was naked in the picture, lying on her dad's chest, while Kim was sitting next to them dressed in a white wedding-style gown.
"North peed on him right at that moment," said Kim. "He was trying to tell me and I couldn't really hear him. Then I had to get up, get her, clean her off, clean him off…"
Kim, 33, told US talkshow host Seth Meyers that she felt like Carrie Bradshaw in Sex and the City during the photoshoot, as she was trying on beautiful wedding gowns while shooting for an iconic magazine.
"I even had to fly to London to meet Sarah Burton from Alexander McQueen," added Kim. "That was a top secret mission on itself. I landed, all the paparazzi were there, and I had to get away from them and figure out how to get to this office without anyone seeing me."
Kim said she had no idea Anna Wintour would choose her and Kanye for the Vogue cover until she saw it, but said that in London she knew if the photoshoot had leaked before it had been announced then they'd have had no chance of a cover.
Got an iPad or iPhone? Reveal Mag is specially designed to fit!
Kim's best bikini moments in pictures:
Copyright: Rex Features Startraks Photo/Rex Features