The Hong Kong site is not subject to the same censorship rules as in mainland China.
"Users visiting Google.cn are now being redirected to Google.com.hk, where we are offering uncensored search in simplified Chinese, specifically designed for users in mainland China and delivered via our servers in Hong Kong," David Drummond, Google's chief legal officer, said on the company's blog.
The switch throws the burden on China to use its own internet filters to prevent Chinese users from seeing images and sites it deems politically or socially undesirable.
On Tuesday, Al Jazeera's own testing of the Google.com.hk site accessed from Beijing showed that while search terms such as "Tiananmen Square massacre" and "Tibet freedom" did yield results, the links themselves were not accessible.
Google stunned many in the online world in January when it said it would stop filtering searches and threatened to pull out of China altogether after uncovering what it said were sophisticated cyber attacks against its systems and email accounts used by Chinese activists.
Google entered the Chinese market five years ago and had previously said it would follow Chinese law requiring service providers to censor access to sites banned by the government.
Al Jazeera's Tom Ackerman reports on the censorship row between Google and China
Following January's announcement the firm said it was engaging in talks with the Chinese government on the issue.
In recent weeks though China has repeatedly stuck to its position that any firm operating in China must follow Chinese laws, apparently leaving little room for compromise.
The State Council official quoted by Xinhua following Google's announcement said the government had twice talked to the firm to try to resolve the standoff but suggested that China's censorship laws were not up for negotiation.
"We made patient and meticulous explanations on the questions Google raised… telling it we would still welcome its operation and development in China if it was willing to abide by Chinese laws, while it would be its own affair if it was determined to withdraw its service,'' the official said.
"Foreign companies must abide by Chinese laws and regulations when they operate in China."
It was not clear whether Google cleared its move with the Chinese government or gave officials any prior notice of the changes.
China could retaliate against the firm by blocking access to its search services entirely, much as it has completely blocked access to YouTube, Facebook and Twitter.
Google has said it intends to keep its office in Beijing and continue to its sales, research and development operations in the world's largest online market.
On Tuesday in the wake of the announcement the company said it was "business as usual" in its China offices, although lay-offs and redeployments of staff remained a possibility.
"We haven't worked out all the details so we can't ever rule out letting people go but we very much want to avoid that," Jessica Powell, a Google spokeswoman, told the Associated Press.