The socialite - who recently revealed she is nine weeks pregnant with her second child with boyfriend Scott Disick - says picking out clothes for 23-month-old Mason is more fun than choosing her own clothes although she wouldn't force him to wear anything he's not happy with.
She told E! "I love dressing Mason more than dressing myself. It's so much fun picking out his clothes and making outfits and giving him style. I'll pick one item to start dressing and then I'll build his outfit from that.
"You can make the outfit cute by adding sunglasses. He has these hot Pink ones and I'm not afraid of pink for boys.
"Hats are a fun way to instantly add style. Mason doesn't always keep his hats on, but he starts with it and if he's over it, takes it off. That's fine, I don't force him to do anything or wear anything."
While Kourtney is happy to splash out on Mason's wardrobe - including his extensive collection of Supra hi-top shoes - she has a few tips for other mothers.
She said: "I think with boys, it's all about shoes. I've seen so many little boys and their outfits are so cute and then their moms put kind of dorky shoes on them.
"Kids definitely grow out of their clothes really quickly, so I'm all about mixing and matching. But let the grandmas buy the expensive stuff."