Kyle Nerner will sell most of its cosmetics company for $ 600m (£ 463m).
The 22-year-old brand, including Kylie Cosmetics and Kylie Skin, will be controlled by beauty giant Koti.
Kylie says she is building the brand into "international beauty power".
Forbes announced that it had sales of $ 360 million in 2018, making it the youngest self-made billionaire ever.
Koti's board president called Kylie "a modern-day icon with an incredible sense of beauty."
Its online impact is so powerful that it has reduced the value of the Snapchat stock by $ 1.3 billion (£ 1 billion) when it announced that it was no longer using the app.
The reality TV star launched her brand in 2015 with a lipstick line, and has since branched into face and skin care makeup.
Although the youngest, Kylie is the highest educator in the Kardashian family.
She faced backlash after being declared a "self-made" billionaire, but defended herself by saying that none of her money came from inheritance.
She has more than 151 million followers on her personal Instagram account, as well as 22 million on her Kylie cosmetics account.
Coty, which owns brands like Burberry and Hugo Boss, will own 51% of the company.
It says the deal will be completed in 2020.
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