It said the measures, restricting gaming depending on the player's age, were "to dispel parents' worries".
According to state media, there has been rising concern over Chinese children's excessive gaming habits.
Parents reportedly worry in particular about both the time and money spent playing Tencent's popular King of Glory game.
From Monday, players aged under 12 will be allowed to log in for only one hour a day, and not after 9pm. Older children will be allowed to play for two hours.
Tencent claims the measures are the most strict in the country's booming online gaming industry.
Chinese state media quoted a company spokesperson saying that "even though as of now, China has not yet passed clear regulations dealing with gaming addiction, we have decided to take the lead".
The firm said it was also working on better implementation of its identity verification, so that those who have not yet completed the verification will not be able to play.
King of Glory is thought to have about 50 million daily active users, and there are numerous reports of parents and teachers expressing concern and frustration about children's gaming habits.
Reports range from a 17-year old gamer in Guangzhou diagnosed with cerebral infarction after playing for 40 hours straight, to children using their parent's credit cards to spend thousands of dollars on the game.
Chinese internet giant Tencent has limited the hours that children can play several of its most popular games.