The 19-year-old model has a very close bond with her 18-year-old sister, but admits when her catwalk career took off it initially ''bothered'' Kylie.
She said: ''She's a Leo so she loves attention, and at certain points when we were younger, it bothered her that I was getting attention in terms of my modelling. I think that's a natural younger sister thing - to be jealous. I was jealous of her sometimes too! But now she loves what I do and supports me. She's very into fashion and always texts me when I'm doing a big show like, 'That is the sickest thing ever! How were the clothes?' It's as much a part of her life as it is mine.''
Meanwhile, Kendall believes she and Kylie are ''much braver than'' their older half-sisters, Kourtney, Kim and Khloé Kardashian.
Speaking in Cosmopolitan magazine's 50th anniversary issue - which features Kendall, Kylie, Kim, Khloe, Kourtney and their mother Kris Jenner on the cover - Kendall said: ''Kylie and I are both pretty brave - much braver than the Kardashians. We have the Jenner in us.''
But she also says her father Bruce Jenner's decision to transition into a woman, now known as Caitlyn Jenner, has brought the entire family much closer together.
Kendall also revealed she and Kylie knew their dad had an issue with his gender because of things they discovered when they were younger and experiences they shared with Bruce.
She explained: ''With our dad, my sisters and I, we all had our experiences with it, but for Kylie and me, being the closest in age, we had our intimate moments of catching him or finding things. Those moments were me and Kylie only, so we had a different connection with it. My dad is my dad, he's their dad too, but he's my blood. I was Daddy's girl and was so obsessed with her - same as Kylie - we spent every day with my dad, so it had a special effect on both of us.''