The rehabilitation centres employ a carrot and stick approach, combining counselling workshops in pottery and drumming with the discipline of a military boot camp.
'Patients' are banned from all internet use and allowed no more than one hour per day on their mobile phones.
"Korea has been most aggressive in embracing the internet. Now we have to lead in dealing with its consequences," Koh Young-sam, head of the Jump Up Internet Rescue School, told The New York Times.
Industry experts fear that web addiction could spread beyond South Korea to neighbouring China, the world's second largest internet market after the US.
In September, a man from the southern Chinese province of Guangdong reportedly died after a non-stop, three-day online gaming session.