The video streaming service has switched off the comments feature on almost every video on its site which features under 18s, in an attempt to "better protect children and families".
The move comes after several brands stopped advertising on YouTube after discovering that child sex predators were leaving inappropriate comments on videos of children.
And after originally disabling comments on videos that were attracting predatory and obscene comments, YouTube has now made the move to disable comments on almost all videos of minors by default.
In a blog post, YouTube wrote: "Over the past week, we disabled comments from tens of millions of videos that could be subject to predatory behaviour. These efforts are focused on videos featuring young minors and we will continue to identify videos at risk over the next few months. Over the next few months, we will be broadening this action to suspend comments on videos featuring young minors and videos featuring older minors that could be at risk of attracting predatory behaviour."
In addition, YouTube will also launch a new comments classifier, which will identify and remove predatory comments without affecting the monetisation of the video itself.
And the site will also take more severe action on creators who "cause egregious harm to the community", by terminating certain channels that attempt to endanger children in any way.
YouTube says it understands that comments are a "core part" of YouTube, but that action needed to be taken to protect the content on its site.
In the blog post - which was addressed to creators on the site - they added: "We recognise that comments are a core part of the YouTube experience and how you connect with and grow your audience. At the same time, the important steps we're sharing today are critical for keeping young people safe."