More than 30,000 blog or microblog accounts were also closed during a campaign that started late last month, according to a statement released by the State Internet Information Office (SIIO).
Among the websites were several photo-sharing, video-sharing and gaming websites that were not registered with the government, state-run Xinhua news agency quoted the statement as saying.
Over 79,000 tips regarding more than 450 websites were received during the campaign, the statement said.
The SIIO, together with the Ministry of Industry and Information Technology (MIIT) and the Ministry of Public Security, is investigating enterprises that illegally allow providers of obscene content to obtain Internet access, as well as people who run pornographic websites, according to the statement.
A separate campaign to prevent gaming and video-sharing websites from offering obscene content will also be carried out.
The office urged tougher measures to punish website operators that profit from spreading obscene content or offering illegal Internet access.