The decision was taken in response to content that “denies, minimises or trivialises” the Russian invasion, a spokesman said.
The world's most used streaming video service said the war falls under its violent events policy and violating material would be removed.
YouTube declined to say which and how many channels had been blocked, or if they ever would be restored.
Workers across Google, which owns YouTube, had been pushing for the platform to take additional punitive measures against Russian channels, accusing them of spreading false narratives about the Ukrainian leadership and civilian deaths during the war, according to three employees at the company.
It earlier banned leading Kremlin-backed channels RT and Sputnik across Europe, as social media companies moved to restrict Russian propaganda and misinformation regarding the invasion.
Facebook, Instagram and video-sharing platform TikTok also blocked the two channels.
Twitter and Alphabet, parent company of YouTube and Google, have suspended advertising in Russia, citing concerns over public information.
And Alphabet said it would suspend all payment-based services in Russia, including YouTube subscriptions.
Russia has taken aim at social media sites, banning Facebook and Twitter shortly after the invasion began.
Meta, parent company of Facebook and Instagram, on Thursday announced that it would change policy to allow users of the sites in Ukraine to call for violence against Russians and President Vladimir Putin.
Moscow responded by designating the US tech giant as an "extremist organisation" and opening a criminal investigation into the company.
“A criminal case has been initiated ... in connection with illegal calls for murder and violence against citizens of the Russian Federation by employees of the American company Meta, which owns the social networks Facebook and Instagram,” Russia's Investigative Committee said.
Meta Global Affairs president Nick Clegg said the company aimed to protect rights to speech as an expression of self-defence for Ukrainians.
Roskomnadzor, Russian communications and media regulator, said it would restrict national access to Instagram because of the policy change.
The state censor has been engaged in a campaign against independent media as the Kremlin seeks to keep on top of dissent among the Russian people over the war, which it maintains is a "special operation" rather than an invasion.
Russia has effectively criminalised news reporting that deviates from the official line with a new law that threatens up to 15 years in prison for spreading what the state deems false information about the war.
The Independent has a proud history of campaigning for the rights of the most vulnerable, and we first ran our Refugees Welcome campaign during the war in Syria in 2015. Now, as we renew our campaign and launch this petition in the wake of the unfolding Ukrainian crisis, we are calling on the government to go further and faster to ensure help is delivered.
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