The system, prompted by demands by the Ministry of Information and Communication Republic of Korea, is designed to filter and delete websites that feature profane sexual content, excluding them from search results.
In order to view those results, age verification software requires users to confirm they are at least 19 years old.
"Our continued efforts with Korean government to come up with the best solution for protecting Korean children and youth form pornographic material has paid off and we are delighted," Google lead attorney Kent Walker said.
The filtering system scans entire keywords, phrases, URLs and open directory searches for adult-related words. Korean Internet portals already have begun compiling a list of "harmful" web addresses, which reportedly has been sent to Google by the country's Internet safety commission.
"Google wants to catch two birds with a stone," said Kim Kyung-mo, an analyst at independent Korean financial group Mirae Asset. "It wants to drum up support for its Korean-language services by improving its corporate image. In addition, the company is complying with the government. It may be a harbinger to indicate that Google is ready to fully compete here after years of struggles."