The deaths highlight weaknesses in the elderly care system in the world's most populous country, whose vast population is ageing rapidly.
He Tiandai, 46, admitted murdering her client, a 70-year-old woman. Prosecutors did not press charges over her other confessions due to a lack of evidence, the official news agency Xinhua said.
The victim's daughter-in-law had promised He a full month's wage in the event of her patient's death regardless of how many days she had worked, according to reports.
He said she would not appeal her sentence, Xinhua reported.
There are deep demographic challenges in China, where holes in the social safety net have left many of the country's aged, and their children, desperate for assistance.
China now has more than 212 million people over 60, according to the National Bureau of Statistics.