YouTube co-founder Steve Chen told Reuters news agency it was hoped that within 18 months the site would "have every music video ever created".
The company said it planned to offer the videos free of charge.
YouTube hosts homemade videos, but pirated commercial clips can be found. It claims 60% of videos watched online in the US are viewed on YouTube.
The site plans to allow users to add the music videos to their own profiles and post reviews.
"Right now we're trying to very quickly determine how and what the model is to distribute this content and we're very aggressive in assisting the labels in trying to get the content on to YouTube," said Mr Chen.
