Unfortunately, 'momager' Kris Jenner turned up on set to support her and ended up stealing the spotlight after paying sartorial homage to the designer.
"Halfway through the shoot, my mum walks in and she's wearing Chanel leggings, Chanel thigh-high boots, blazer, turtleneck, dangling earrings, Chanel cuffs, gloves, sunglasses, beret: She was decked in Chanel from the '80s," the 39-year-old recalled.
"Karl stops the shoot and walks over to her and is like, 'Oh my God, are you her mother? I remember this jacket! I remember these gloves! I did those earrings!'", Kardashian continued.
"The two of them have this love affair like I've never seen before. And I'm like, Hello? I'm sitting here posing. I'm so uncomfortable. I'm like, 'This is so embarrassing, and this is so annoying.'"
Once the shoot was over, Lagerfeld came over to the duo with something hidden behind his back - the famed accessory.
"I'm like: 'THE BAAAAAG. IT'S HEEEERRE. OH MY GOD. I'm thinking: I will cherish this forever, and I'm pregnant, so one day I'll give this bag to my daughter," Kardashian recalled.
According to the Keeping Up With The Kardashians star, it wasn't not any old bag either as it was a sample Lego clutch decked in Swarovski crystals which never made it to production.
But to her dismay, Lagerfeld handed the prized Chanel item over to her mother.
"Then he comes up and he's like, 'Kim, this was the best shoot. Thank you so much. But Kris, here is a bag for you,'" she said.
Horrified by the turn of events, Kardashian ran into the bathroom and started crying.
"I was like, 'Oh my God, she fully stole my life. She stole my whole day today!'" she added.
Six years later, it seems Kardashian is still not over the episode and has vowed to give the heirloom to her six-year-old daughter, North West, in the future.
"To this day, she [Kris Jenner] has the bag in her closet," she added. "And I've said to her: 'Just so we're clear, in your will, this goes to North.' I don't need it. That bag was for my daughter."