The victim's sister found her after becoming concerned, according to neighbors on 175th Street in the Jamaica section.
The victim was identified as Rosemary Little.
She was described as kind-hearted, taking in her grandson after his mom died when he was only 6 or 7 years old.
Detectives later arrested her 26-year-old grandson, Christopher Jackson.
He is charged with 2nd Degree Murder and Tampering with Physical Evidence.
She is the second grandmother found dead in a closet in recent weeks in New York City.