The 26-year-old woman had been “strangled and beaten”, according to the news website 055Firenze.it.
Her body was found on Monday by friends who shared the apartment on Via Pistoise, a road inhabited mostly by Chinese people and nicknamed Prato's "Chinatown".
Police later detained a man, said to be of Asian origin and the woman’s partner. After being interrogated overnight, he reportedly confessed to the murder. The pair shared a room together in the apartment, according to the website.
Prato is home to about 17,000 Chinese nationals, according to official data from 2010, but local sources say the real figure is closer to 50,000.
Thousands of Chinese textile factories have opened in Prato over the past decade.
But their presence is not always welcomed in the city, where numerous Italian firms have been forced to shut, unable to compete.
Despite efforts to clamp down on illegal businesses and dangerous working conditions, shuttered warehouses often reopen elsewhere.