The angler hooked the large fish about 30 nautical miles (55km) off the remote North West Cape on Tuesday.
Another fisherman spotted the man's empty boat travelling at speed and alerted authorities.
The man, believed to be in his 20s, was plucked from the water after several boats joined the search.
Rescuers said the man was incredibly lucky to survive after being found in "the middle of nowhere".
"The boating community that was out there did a very good job at rallying around and getting a search underway as fast as possible," Rusty Ellis, commander of the Exmouth Volunteers Marine Rescue Group, told the BBC.
"I think everybody is extremely relieved that he was found at all. It could have quite easily been a disastrous situation."
The fisherman, originally from New Zealand, was treated at Exmouth Hospital for hypothermia and shock.
Ellis said the incident was a reminder about the dangers of fishing alone.