The girl was at a home on 102nd Street in Corona around 4:30 p.m. when she followed her babysitter to a shed in the backyard to feed a dog, a 1-year-old pit bull named Diesel.
The toddler started playing with the dog's bone and it bit her.
She was taken to Elmhurst Hospital in critical but stable condition.
The girl's parents were at work at the time.
The NYPD's Emergency Services Unit removed the dog from the home, and handed it over to Animal Care and Control.
The incident is being investigated as an accident.