Andrew Wilson, 25, was on his own and was not wearing a life jacket when the wave sent him over the side of his boat Tuesday off the Gold Coast, south of the Queensland state capital, Brisbane.
Police launched an air and sea search for Wilson after his boat was spotted, unmanned and with the engine still running, Tweed Heads Police Inspector Darren Steel told Australian Broadcasting Corp.
Searchers found no sign of the missing man, Steel said. But he turned up ashore after swimming 4.7 miles (7.5 kilometers), clambering over rocks and then knocking on a stranger's door seeking help.
Wilson was treated at a hospital for cuts and exposure, then released.
Later, he told Nine Network television he realized as soon as he was in the water that he was going to have to swim for it.
Strong currents pulling him away from shore meant he could not rest even for a short time.
"I thought I'd be able to stop and be able to float and get some energy back, but if I stopped for 30 seconds it would take me straight back out to sea," Wilson said from his home, wearing board shorts and bandages on his knees.
"There was only going to be one outcome - I wasn't going to stop, so I just kept going," he said. "Adrenaline and just sheer determination."