World of Warcraft: Mists of Pandaria sold through approximately 2.7 million copies in its first week of availability.
Blizzard said the latest expansion helped push the MMO's global user base back above ten million, "with growth across all major regions, based on internal company records and reports from key distribution partners".
In August, Activision Blizzard confirmed World of Warcraft subs stood at 9.1 million, over a million fewer than at the end of the company's previous financial quarter.
The company has attempted to renew interest in the MMO by allowing users to play the first 20 levels for free. Blizzard lead game producer John Lagrave recently said the move gives new players "a good sense of what our game is" and that the studio doesn't plan to raise the WoW free-to-play level cap.
"With Mists of Pandaria, we set out to expand on the sense of fun and discovery that's always been at the heart of World of Warcraft - in addition to adding a huge variety of new content and features to the game," Blizzard CEO Mike Morhaime said today.
"It's been gratifying to see the results of all of the work we put into this expansion and to hear all of the positive feedback from players so far."
The World of Warcraft development team is currently working on the first major post-launch content update Mist of Pandaria, and says further details will be provided in the coming weeks.
Have a read of our World of Warcraft: Mists of Pandaria review for our take on the levels 1 to 20 in the expansion.