The Australian troops will be part of Nato's expanded peacekeeping and reconstruction operations.
"They will work on reconstruction and community-based projects as part of Australia's commitment to securing a stable and democratic future for Afghanistan," said John Howard, the Australian prime minister, on Monday.
Howard said the deployment was a "further reminder of our very strong commitment to the coalition effort in Afghanistan".
The announcement means that more than 500 Australian soldiers will be deployed in Afghanistan.
The deployment had been announced in February but its exact size was not made clear until Monday.
Nato is expanding its operations to allow the larger US-led coalition to reduce its troop numbers to 16,500 from 19,000 and focus on hunting the former ruling Taliban militants believed to be behind a growing insurgency in the country.
Islamist militants and their allies have intensified their campaign against foreign troops and Afghanistan's government in recent months with a wave of roadside and suicide bombings, attacks and assassinations.
Howard said the latest deployment was a reinforcement of the commitment the Australian government made in 2001, when it deployed 1,550 troops as part of the US-led coalition force which ousted the Taliban government.
Australia later withdrew its soldiers, only to redeploy 190 elite special forces troops again in 2005 to counter growing rebel attacks.
"Whilst Afghanistan is remote for Australia, this is very much in the interest of the next generation fighting terrorism in this country," Howard said.