Restaurateur Hasse Johannesson opened 30 oysters in 2 minutes 41 seconds to scoop the coveted award, ahead of Canada's Eamon Clarke by 13 seconds.
"Now I need a cigarette," said Johannesson as he celebrated his first world title after competing for the fourth time.
The secret is not just good timing but in the clean presentation as if you would serve it in a restaurant," he said.
Damage to the oyster's flesh, failure to detach it from the shell, grit or traces of human blood mean penalties for the knife-wielding competitors who have come from 16 other countries including Thailand, the United States and Estonia.
Johannesson received a penalty of four seconds.
"It is the fine balance between speed and quality, that is why it is so difficult," said Terry Brennan, chairman of the panel of seven judges. "It is all about being able to slide the oysters down your throat without difficulty."
The championship is the showpiece of Galway's International Oyster Festival, in its 53rd year, which was dreamt up by a local hotelier to herald the start of the oyster season.
The four-day event expected to generate around 8 million euros for the local economy. Around 100,000 oysters were expected to be consumed.
"Oysters are the taste of the ocean and they are very pure and natural," said Canadian chef and author Patrick McMurray, a past world oyster opening champion. "It has an elemental property which just gives pure happiness to everyone."