YouTube says more than one billion people visit its online video site every month.
It is another milestone in the online video site's evolution from a quirky start-up launched in 2005 to one of the most influential forces in the media landscape.
YouTube crossed the 1bn threshold five months after Facebook said its online social network had reached that figure for the first time.
In a blog post, the YouTube team noted that nearly half of all internet users visit the website.
"If YouTube were a country, we'd be the third largest in the world after China and India," said the YouTube team.
Google bought YouTube in 2006 for $1.65 billion (€1.28bn) and has yet to disclose whether the service has turned a profit.
The video-sharing service says it is trying to "marry the best of TV and the best of online".