Search efforts launched after Robert Weber, 58, went missing in the state of Queensland were called off this week.
But police said he had been found near a dam on Sunday by a “property owner”, who has been identified in Australian media as a local politician.
Mr Weber was “suffering exposure to the elements” but otherwise safe and well, police said.
Before Sunday, he had last been seen leaving a hotel in the town of Kilkivan with his dog on 6 January. He ran into trouble when his car got stuck in dirt on a farm road.
Police said Mr Weber spent three days in the car before running out of water and setting off on foot. He then became lost but remained near a dam where he survived by “sleeping on the ground, drinking dam water and eating mushrooms”.
An extensive air and ground search was suspended after failing to find him, but local property owners and police were told to keep an eye out.
Local MP Tony Perrett and his wife were reported to have found Mr Weber on Sunday just 3km (1.9 miles) from where his car had been discovered, after searching their cattle farm.
“He was sitting under a tree near a dam waving at us,” Mr Perrett told ABC.