Online gamers under the age of 18 will only be allowed to play for an hour on Fridays, weekends and holidays, China's video game regulator has said.
The National Press and Publication Administration told state-run news agency Xinhua that game-playing would be only allowed between 8pm to 9pm.
It also instructed gaming companies to prevent children playing outside these times.
Earlier this month a state media outlet branded online games "spiritual opium".
Inspections of online gaming companies will also increase, to check that the time limits are being enforced the regulator said.
Earlier rules had limited children's online game-playing to 90 minutes per day, rising to three hours on holidays.
The move reflects a long running concern about the impact of excessive gaming on the young.
A month prior to the latest restrictions, an article published by the state-run Economic Information Daily claimed many teenagers had become addicted to online gaming and it was having a negative impact on them.
The article prompted significant falls in the value of shares in some of China's biggest online gaming firms.
In July, Chinese gaming giant Tencent announced it was rolling out facial recognition to stop children playing between 22:00 and 08:00.
The move followed fears that children were using adult ID's to circumvent rules.
China clamps down on 'spiritual opium'
Zhaoyin Feng, BBC News
It's probably a disappointing end of summer for China's tens of millions of young gamers.
The Chinese authorities have long been concerned about gaming addiction and other harmful online activities among youth.
Beijing appears to show a growing scepticism over the expansion of capital and technology, as well as its potentially adverse impact on the well-being of the country's young generation.
The new rule came amid a sweeping crackdown on China's tech giants, such as Alibaba, Didi and Tencent, as well as a series of reforms over activities considered by Beijing as harmful to the young generation, including celebrity fan culture and private tutoring.
By imposing these new rules, the Chinese government is hoping to create "positive energy" among young people and to educate them with what Beijing considers "correct values".
While many Chinese parents may applaud the gaming restriction, some on China's social media Weibo criticise the government interference as being "unreasonable" and "arbitrary".
"Why don't you plan when I go to the toilet, eat meals and go to bed," one sarcastic comment read.