Twenty prisoners were involved in the standoff, which began Saturday when inmates occupied part of Risdon Prison on the southern island state of Tasmania, complaining about conditions in the aging institution and taking guard Ken Hannah hostage.
Hannah finally was released late Sunday night after authorities caved in to demands for pizza.
"The final sticking point with the inmates was that they were requiring pizzas to be delivered," said senior prisons official Graeme Barber.
"We had held off in relation to that — we obviously wanted the release of our staff member," he added. "Our staff member was negotiated out by the delivery of 15 pizzas."
The last prisoner involved in the siege gave himself up Monday. No one was injured.
The siege followed months of violence and unrest at Risdon, which holds one of Australia's most notorious convicts, Martin Bryant, who went on a shooting rampage at Tasmania's Port Arthur historic penal settlement in 1996, killing 35 people.