Hugo Barra said in a note posted online that he was pursuing "a new career chapter." His job at Xiaomi will be to "help them expand their incredible product portfolio and business globally," Barra said.
He said he was "particularly excited about the opportunity to continue to help drive the Android ecosystem," which implies he is not leaving Google completely behind.
PCMMag.com reported Thursday Barra was the latest of recent key departures from the Android team.
He is one of the highest-profile Westerners to join a Chinese technology company, an analyst said.
"He's a significant figure in the industry, a significant figure at Google," Pete Cunningham at research firm Canalys told The New York Times. "It underlines the trend we're seeing in the market. The Chinese vendors are going to play a big part in shaping the future of the industry."
Google merged the operations of Google and Chrome in March, displacing Andy Rubin as head of Android.
The task of leading Google and Chrome was assigned to Sundar Pichai.
Smartphone maker Xiaomi has made it its mission to emulate U.S. technology giant Apple, the Times said in an article in 2012.
"Xiaomi's marketing strategy has been to ride on the back of the 'cult of Apple" and of its creator [Steve Jobs]," the Times reported.
The company launched its first smartphone in September 2011 and has said sales reached 7 million by the end of 2012, PCMag.com reported.