That makes her the youngest billionaire in history, and the youngest self-made billionaire ever, according to Forbes, which included Jenner on its list of the world's billionaires, released on Tuesday.
Jenner took the title from Facebook co-founder Mark Zuckerberg, who became a billionaire in 2008 at age 23, and Microsoft co-founder Bill Gates held it in 1987 at age 31.
Jenner's latest boost in wealth comes primarily from Kylie Cosmetics, her makeup company, which Forbes now values at $900 million. Kylie Cosmetics, which is projected to rake in $1 billion in lifetime sales by 2022, signed an exclusive distribution deal with the retailer Ulta last summer that quickly boosted sales for Jenner's company (Forbes says Kylie Cosmetics sold $54.5 million worth of products in Ulta stores over the first six weeks of the deal). Jenner says that she plans to work on the company "forever" and then pass it down to her daughter, Stormi, who recently celebrated her first birthday.
"I didn't expect anything. I did not foresee the future," Jenner tells Forbes of her business success. "But [the recognition] feels really good. That's a nice pat on the back."
Some critics on social media have taken issue with the description of Jenner as self-made because she was born into wealth and fame. (Details about Forbes' methodology and criteria can be found here.) Either way, Jenner's entrepreneurial efforts are impressive. She's the most financially successful member of the Jenner-Kardashian family: Her older half-sister Kim Kardashian West has an estimated net worth of $350 million.
Aside from Kylie Cosmetics, Jenner earns money from her paid app, the "Kylie Jenner Official App," as well as sales of merchandise from "The Kylie Shop," two apparel lines with sister Kendall Jenner, a book series, TV programs including "Keeping Up With the Kardashians" and "Life of Kylie," and other partnerships with retail brands like Adidas, Topshop and Quay Australia.
Jenner launched her beauty brand on November 30, 2015, with the $29 Kylie Lip Kit, a liquid lipstick with a matching lip pencil, which sold out in just minutes. Within 18 months, the company had made $420 million in sales. Her 2016 holiday collection release made nearly $19 million in one day. For comparison, Kardashian West's first product launch from her new makeup brand KKW Beauty earned an estimated $14.4 million in sales.
In any event, Jenner says she isn't too concerned about competition with Kardashian West, with whom she initially collaborated for Kylie Cosmetics, because they each reach a different demographic, she tells WWD. "She's, like, almost 20 years older than me. I feel like my makeup is definitely more young, fun. And it's just different," Jenner says.