The man was detained shortly after the flight departed for Kuala Lumpur when he ran towards the cockpit brandishing a music speaker he claimed was a bomb.
He was tackled by passengers and restrained until the aircraft returned to Melbourne, where the Airbus A330 was stormed by armed police.
"He ran down the back aisle and three great Aussie heroes wrestled him to the ground and totally immobilised him," a witness told the BBC.
A lengthy search of the aircraft was carried out amid reports of a second possible device as the man, a Sri Lankan national, was arrested. Passengers criticised the 90 minute-wait before they were allowed to disembark, but security forces said they had had to be sure the man was acting alone.
