The man had plummeted at least 180ft in an apparent suicide attempt yesterday.
Niagara Parks Police said witnesses saw him climbing over a railing and "deliberately jump" into the Niagara River at Horseshoe Falls – the highest of three falls.
He surfaced in the lower Niagara River basin and made his own way to the bank.
But fire chief Dan Orescanin said he appeared to have sustained chest injuries including broken ribs and a collapsed lung.
He said: “He waded ashore. He must have gotten swept into an eddy, floated over there and was able to get out on his own.
Rescue ... winched to safety
“That's another stroke of luck. If he was in the main current, he would have been swept down river.”
Firefighters had to rappel down the rocky gorge and carry him high enough up the cliff for him to be winched up in a bright yellow rescue basket.
Niagara Parks Police Sgt. Chris Gallagher said: “Based on witness statements and surveillance video, it doesn't appear in any way, shape, or form that this was anything other than a suicide attempt.”
The last person to survive a plunge over the Falls unaided was a 30-year-old Canadian man in March 2009.
