I know Google is a gigantic, pro-state corporation, but this is a very anarchistic move on their part. They are basically rebelling against China.
China has said Google's move to stop censoring search results is "totally wrong" and accused it of breaking a promise made when it launched in China.
The US giant is redirecting users in mainland China to its unrestricted Hong Kong site, although Chinese firewalls mean results still come back censored.
Beijing said the decision should not affect ties with Washington.
Google threatened to leave the Chinese market completely this year after cyber attacks were traced back to China.
Google's move effectively to shut its mainland Chinese search service, google.cn, is a major blow to China's international image, the BBC's Damian Grammaticas reports from Beijing.
It means one of the world's most prominent corporations is saying it is no longer willing to co-operate in China's censorship of the internet, our correspondent says.
In Beijing, some passers-by laid flowers outside Google's offices to thank the company for standing up for its principles.