When she was denied testing three times at a local hospital, she flew to China, where she tested positive upon arrival, the officials said.
She is reportedly one of China’s 114 coronavirus cases imported from foreign countries, which have become a growing concern for its authorities.
Five million people left Wuhan, the Chinese city where Covid-19 was first identified, before the city went into lockdown in January.
However, some Chinese people living abroad have been forced to return to the country for coronavirus testing as foreign governments have failed to implement widespread checks for the virus.
The case in Massachusetts was reported by Beijing News after a news conference by health authorities on Saturday.
Pang Xinghuo, deputy director of the Beijing Centres for Disease Control and Prevention, said the woman began to fall ill on 1 March and developed a high temperature of up to 39C.
A health declaration card which was filled upon her arrivals showed she had symptoms of fever, fatigue and a dry cough, while her husband had symptoms of fatigue and her son had no symptoms, Beijing News reported.
Ms Li was diagnosed as a confirmed case of coronavirus and her husband and son were diagnosed as suspected cases on Friday.
Her condition is currently stable and she is being isolated and treated in hospital.
China was praised by the World Health Organisation for its response to Covid-19 after it introduced strict quarantines and social distancing measures to control the outbreak.
The country has reported low numbers of new cases in recent days and Chinese authorities have now moved towards loosening restrictions on movement and allowing employees to return to work.
However, it is unknown at this time whether China will see a new spike in infections when its citizens begin to return to normal life.