The 19-year-old model regularly borrows her sister's outfits, with the 17-year-old television personality only realising once she sees Kendall post pictures of her in the clothes on Instagram.
She said: ''Every time I am out of town she will be at the house and just have a free-for-all and go through everything, take whatever she wants.
''And I will see it on Instagram the next day. She takes my new stuff all the time.''
The 'Keeping Up With The Kardashians' star has joked it has become so bad that the pair have made a pact not to nick anything from each other.
She added: ''I used to take her stuff all the time, but we don't live together anymore, so she won't even let me in her home when she's not there, because she's scared I am going to steal something. Or she will have someone watch over me, because we have a rule now not to steal anything from each other.
''But I live with my mom - I'm about to move out - so she just goes into my closet and takes whatever she wants. It is so annoying. I am like, 'We don't live together. You can't take my stuff and I won't take yours!'''
Despite not wanting to share her many clothes, Kylie has admitted she isn't able to wear all of the outfits in her wardrobe and feels incredibly ''guilty'' about wasting the beautiful gear.
She added to PEOPLE magazine: ''There's so much stuff. I feel so guilty!
''A lot of heels that I will just never wear. I am like, 'This is my new heel,' but I still won't wear it.''
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