The 30-year-old woman was rushed to the Deen Dayal Upadhyay hospital, but died on the way, jail authorities said.
There were two other inmates lodged in the same cell, but they were out on work when the incident happened.
On Monday, Ram Singh, one of the six men accused of brutally gang-raping a medical student on a bus in Delhi, was found dead in his cell in Tihar. He allegedly committed suicide. His family and lawyers, however, allege that he was murdered.
Ram Singh's death has raised questions about security at the Delhi prison. The four other men accused in the Delhi gang-rape case and lodged at Tihar have reportedly been shifted to cells with CCTV surveillance.