The rules will apply to users under 14, who have been authenticated using their real names, and who will be able to access it between 06:00 and 22:00.
Parent company Bytedance announced the app’s Youth Mode in a blog post, saying it is the first short-video company in the industry to have these limits.
It comes as China cracks down on teenagers' use of technology.
According to Douyin's user agreement there is no minimum age on the platform, but under 18s must obtain the consent of a legal guardian. On sister app TikTok the minimum age is 13.
New educational content - including science experiments, museum exhibitions and historical explainers - has been launched by Douyin as part of Youth Mode.
“Yes, we are more strict with teenagers. We will work harder to provide quality content so that young people can learn and see the world,” the post said.