Bronx District Attorney's office spokesman Steven Reed says jurors found 25-year-old Sparkle Daniel guilty of second-degree murder on Wednesday.
She faces a maximum of life in prison when she's sentenced Oct. 25.
Prosecutors say Daniel and another woman poured wine down 91-year-old Nellie Hocutt's throat and stuffed her mouth with a piece of cloth before suffocating her with a plastic bag.
They say the suspects bound the woman to a chair with tape and a telephone cord.
At the time of their arrest in 2007, police said the women had decided to rob Hocutt of a gold chain and some towels.
Daniel's relatives have disputed the charges against her.
The second defendant is awaiting trial.