The company is now the fourth-biggest seller of smartphones worldwide, right behind Huawei, according to Gartner.
Xiaomi sold 15.8 million units in the third quarter of this year, a 322 percent increase from the same period a year ago, when Gartner reported it sold 3.6 million units.
Xiaomi isn't the only Chinese smartphone-maker that saw growth in sales year over year.
Three of the top five smartphone-makers worldwide are Chinese companies including Huawei, Xiaomi and Lenovo. Collectively, these three companies accounted for about 15 percent of all smartphone sales in the third quarter.
The other two leading handset companies were Samsung, which sold 73.2 million units, and Apple, which sold 38.2 million smartphones.
Apple's iPhones sales grew 26 percent from a year ago, while Samsung's sales dropped 10.8 percent, according to Gartner.
In China alone, which is Samsung's biggest market, its sales fell 28.6 percent.