"We are blocking the YouTube channels of RT and Sputnik in the whole of Europe with immediate effect. Our systems need a little time before being fully operational," YouTube said in an email to AFP.
Fellow online giant Facebook took a similar decision on Monday by blocking content published by RT and Sputnik in the European Union.
The state-backed media organisations are considered mouthpieces of Russian President Vladimir Putin's regime.
European Commission chief Ursula von der Leyen on Sunday announced they and their subsidiaries would be banned from broadcasting in the bloc for spreading "lies to justify Putin's war".