The girl, identified only as "Sohana," told a news conference she was kidnapped on her way to school in Peshawar by two men and two women, The Christian Science Monitor reported Wednesday.
Sohana said the Taliban militants drove her to a large town bordering Afghanistan and instructed her to attack the Darra Islam checkpoint.
The third-grader managed to escape her captors while they were fitting her in a suicide vest.
Farzana Bari, a leading human rights activist, said Sohana's experience validates fears the Taliban are increasingly using children as weapons.
"I believe the Taliban are becoming desperate," she said. "It is worrisome that now they (the Taliban) want to destroy the young generation and use these innocent kids as their soldiers in the name of holy war."