The 39-year-old star has a huge collection of expensive garments and rather than recycle them or give them away she is stockpiling them to give Penelope, six, when she is grown up.
Speaking to PEOPLE, she revealed: "I just wore this little black Dolce & Gabbana dress in Italy and I posted a photo - I was with Domenico Dolce - and I saved that dress for her. I was like, 'She needs to have this someday.'
"I save things all the time and she always tells me, 'Can I have this? Can I have this?' And I'm like, 'What's mine is yours.' "
Kourtney admits Penelope is already very fashion conscious for a child and is obsessed with her famous mother's collection of designer handbags.
And Kourtney - who also has sons, eight-year-old Mason and three-year-old Reign, with her former partner Scott Disick - lets Penelope use some of her smaller bags now.
She added: "She likes to wear my bags a lot and I love mini bags, so I take a lot of her bags too."
For Kourtney family is everything and she is delighted that her sisters Kim Kardashian West, Khloe Kardashian and Kylie Jenner have all had babies this year as it means the tots can grow up together.
Speaking about the births of Khloe's daughter True, Kim's girl Chicago, and Kylie's daughter Stormi, Kourtney said: "I think it's really special to have three little baby girls all at the same time. We call them the triplets."
It isn't just the three new additions that are around the same age either, as Kim's other two children - five-year-old daughter North and two-year-old son Saint, whom she has with her husband Kanye West - are very close with Kourtney's youngest kids too.
The 'Keeping Up with the Kardashians' star added: "To have all of our kids be able to grow up together and there's one after the other, I feel like we're all so blessed. We love it - it's the best energy. We were just hanging out with all the kids outside and it's really amazing."