"Unfortunately, she went into a coma for some time after suffering from brain damage. She died a few minutes ago," IRNA reported.
Armita had been pronounced brain dead last week after she fell into a coma on October 1 after she suffered "severe injuries" following an alleged altercation with the morality police at Shohada station in the Iranian capital Tehran.
Armita was later seen unconscious in hospital with a respiratory tube and a bandage over her head in photos published on social media by rights groups such as Kurdish-Iranian Hengaw. The images have not been verified.
Iran has denied that Geravand was hurt after a confrontation on October 1 with officers enforcing the mandatory Islamic dress code in the Tehran metro.
The death of 22-year-old Mahsa Amini in the custody of morality police last September sparked months of anti-government protests that spiralled into the biggest show of opposition to Iranian authorities in years.
Women are required by law to cover their hair and wear long, loose-fitting clothes in Iran, where the secular and Western-backed Shah was deposed in a revolution in 1979.
Violators face public rebuke, fines or arrest yet defying the strict Islamic dress code, more women have been appearing unveiled in public places such as restaurants and shops since Ms Amini's death.