The victim, daughter of a garment factory worker, was allegedly raped by a plus-two student when she was playing alone in her house on September 17.
The 16-year-old boy was arrested a few days later.
The girl, who underwent treatment in a government hospital in Tirupur, was shifted to a private hospital later. She was discharged a couple of days ago.
Even as the parents were planning to take the child for further treatment to Delhi, her condition worsened yesterday and was admitted to government hospital here, where she died during the early hours today, police said.