The Cyberspace Administration of China said the companies had promised to "handle in a timely way terror-related harmful, illegal information, create a clear Internet space and maintain social stability".
The companies which have signed up include Baidu Inc, Tencent Holdings Ltd, Alibaba Group Holding Ltd, JD.com and Sina Corp, the regulator said.
Tencent, Alibaba, JD.com and Sina did not immediately respond to request for comment. A Baidu spokesman declined to comment.
The regulator said that more than 25,000 posts, 4,000 videos and 200 accounts had been removed from the Internet so far this year that involve illegal, terror-related content.
China passed the anti-terrorism law in December. Among other things, it requires technology firms to help decrypt information and cooperate with the government in fighting terrorism.
Critics say China uses its counter-terror and national security regulations to quell free speech.
Under President Xi Jinping, the government has implemented an unprecedented tightening of Internet controls and sought to codify the policy within the law.
China has rebuffed the criticism of the law, saying it is simply doing what other Western nations already do in asking technology firms to help fight terror.
The law has caused particular unease in Western capitals as it codifies sweeping powers for the government to combat perceived threats.
China says it faces a serious threat from groups such as the East Turkestan Islamic Movement (ETIM), which operates in China's restive far western region of Xinjiang, home to the Muslim Uighur people, where hundreds have died in violence in recent years.
Rights groups and many foreign experts though say China has never presented any convincing evidence to prove ETIM exists as a cohesive, well-organised group capable of the kinds of attacks China blames it for.
© Thomson Reuters 2016
Get your daily dose of tech news, reviews, and insights, in under 80 characters on Gadgets 360 Turbo. Connect with fellow tech lovers on our Forum. Follow us on X, Facebook, WhatsApp, Threads and Google News for instant updates. Catch all the action on our YouTube channel.
Samsung Galaxy Watch 9 (44mm, LTE)
Starts from ₹44,999
Samsung Galaxy Watch 9 (40mm, LTE)
Starts from ₹37,999
Samsung Galaxy Watch 9 (40mm)
Starts from ₹37,999
Haier M70 Mini LED 65-inch
Starts from ₹74,990
CMF Buds Neo True Wireless Stereo (TWS) Earphones
Starts from ₹2,199
Xiaomi TV FX Mini LED 65
Starts from ₹64,999
IFA 2026: Lenovo Unveiled New IdeaPad, Yoga and ThinkBook Laptops
IFA 2026: Nvidia RTX Spark PCs, Local AI Tools Announced With October Launch Planned
Luna Band Now Available Globally: Check Price in India, Specifications and Features