Kerry Jane Wilson, 60, was working with an NGO when she was taken from the company's office in Jalalabad by armed men in military-style uniforms.
She is now "safe and well", according to Australian Foreign Minister Julie Bishop, who gave no further details.
Jalalabad is close to the border with Pakistan, in a region where militant groups are known to operate.
Ms Wilson, known also as Katherine, is the director of Zardozi, a charity which helps poor women start their own businesses.
She had been working in the region for 20 years before she was kidnapped by the unidentified gunmen.
Ms Bishop said the government would not comment on the circumstances of her release to "protect those who remain captive or face the risk of kidnapping".
However she added that she "deeply appreciated the work of the authorities in Afghanistan whose support and assistance facilitated (Ms Wilson's) release".
Australia says it does not pay ransoms for hostages.
Ms Wilson's 91-year-old father, Brian Wilson, had earlier told the Australian Broadcasting Corp he was extremely worried about his daughter, but that the kidnappers would probably keep her alive.
An Australian aid worker who was abducted in Afghanistan earlier this year has been released.