Mark Wylie, from Calne, beat off competition from 24 criers from around the world to take the title in Bermuda.
Entrants in the three-day event were judged on "sustained volume" from a 20m (65ft) distance, diction and bearing among other things.
Mr Wylie, who almost lost his voice in the effort, said: "I decided to give it my all and my all is what it took."
Having been Calne's town crier since 2007, Mr Wylie normally dons a heavy, "made-to-fit" uniform in the colours of the town's flag.
But to compete in the tropical heat, a special lightweight cotton outfit had to be made.
"My normal regalia is 100% wool and I would have melted in that," he said.
"So my wife made me a new set which was the right weight and very comfortable to wear."
Held over three days with a different cry staged each day, Mr Wylie managed to oust the reigning world champion - Canadian Chris Whyman - by winning all three.
"My voice is better than it was but it's still rough," he said.
"Some criers seem to be able to bellow for as long as they like and it doesn't affect them at all.  I'm not too bad usually but in the final round, I could feel it was already pretty hoarse."
Despite almost losing his voice in the final stages of the competition, the Wiltshire crier not only took the championship trophy but the winner's reward as well.
"It was an awful lot of rum, would you believe, which I need for medicinal purposes," he said.
A Wiltshire man has become the "first Brit" to win the title of International Town Crier.