Yahoo, Microsoft's MSN and other blog providers in China this week signed the "self-discipline" pact, under which they pledged to "safeguard state and public interests," according to a statement from the China Internet Society.
The pact "encourages" the Internet firms to register the real names, addresses and other personal details of the bloggers, and then keep this information.
The firms also committed to delete any "illegal or bad messages", according to a copy of the pact posted on the society's website.
Along with sex and violence, China's communist rulers have also deemed that opinions critical of it or the spreading of democratic ideology are not allowed.
Yahoo China and MSN told AFP they had signed the pact, but did not give any further comment.
"I can confirm that we signed the pact this week," Yahoo China's Beijing-based spokesman Dou Xiaohan said.
MSN China spokesman Feng Jinhu said: "We've signed the pact but there is no press release on that. On your other questions, we will get back to you as soon as possible."
US Internet companies such as Yahoo, Microsoft and Google have previously caused uproar abroad for bowing to the Chinese government's demands by agreeing to censor websites and content banned by the nation's propaganda chiefs.
They have repeatedly insisted that they have no choice but to follow local rules and regulations in China.
Yahoo came under particular criticism for cooperating with requests by China to pass on personal information of its users, leading to the jailing of several cyber-dissidents.
International press freedom group Reporters Without Borders condemned Yahoo and MSN for agreeing to the blogging pact.
"The Chinese government has yet again forced Internet sector companies to cooperate on sensitive issues. In this case blogger registration and blog content," it said in a statement.