Reg Foggerdy disappeared last week while pursuing a feral camel in a remote area of Western Australia state.
Police trackers found him sitting under a tree on Tuesday morning around 15km (9 miles) from where he became lost.
His family described him as an experienced bushman but have now told him to buy a satellite phone.
Mr Foggerdy's wife Arlyn told AP she had cried when she heard he had been found alive.
"How you can survive without water and food is a miracle,'' she said.
Wearing only a T-shirt, shorts, a cap and flip-flops when he went missing, Mr Foggerdy - a retired miner - apparently became disorientated in the fierce heat of the desert.
He was discovered "extremely dehydrated, a bit delusional, but he's received treatment, first aid on the ground, and it's fair to say he's now sitting up and talking," Police Supt Andy Greatwood told ABC radio.
Supt Greatwood also praised Mr Foggerdy's "fantastic" skills, saying that while more details of how he coped were likely to emerge, "most people would not have survived".
"The amazing news is his last couple of days of survival were achieved by lying down under a tree and eating black ants, so that's the level of survival that Mr Foggerdy has gone to," he said.
Mr Foggerdy's sister Christine Ogden told the West Australian she had not given up hope.
"When I went to bed last night, I said: 'Tomorrow's the day, they're going to find him.' I didn't know which way it was going to go, but I just had this feeling."
A 62-year-old Australian man lost for six days in the Outback has been found alive after surviving without water and by eating ants, say police.