YouTube prohibits threatening or intimidating individuals or groups in the name of the QAnon conspiracy theory.
The company is also taking action against other conspiracy theories that have been used in the real world to justify violence, such as Pizzagate.
QAnon is the umbrella name for multiple conspiracy theories that boil down to US President Donald Trump fighting behind the scenes against a group of people trying to undermine him.
Supporters of QAnon's accusations include prominent Democrats and Hollywood stars of pedophilia and Satanism.
They also argue that at some point Trump will make short work of his opponents by triggering 'the storm'.
QAnon builds on Pizzagate, a conspiracy theory that was popular around the 2016 US presidential election. The conspiracy theory revolves around an alleged underground child abuse network in a pizza restaurant basement, which also involves Trump's rival Hillary Clinton.
None of the above allegations are based on evidence.
Videos and posts about these types of conspiracy theories will be removed by YouTube from Thursday if they target a person or group, the company announced on its blog.
"As always, context is important," YouTube said.
"So news coverage on these topics or content discussing conspiracy theories without targeting individuals or groups can remain."
See also: What is QAnon, the conspiracy theory that provokes 'war between realities'?