Gearbox's shooter overtakes this year's previous record holder Mass Effect 3, racking up more than 4,000 additional week one sales.
It's also outselling its predecessor by a margin of 4 to 1, making 71% of sales on the Xbox 360, compared to 22% on the PS3 and 7% on the PC.
Strong first-week sales ensured that Borderlands 2 topped this week's all-format, PS3, Xbox 360 and PC charts, ahead of fellow new releases F1 2012 and PES 2013.
Released in Europe and North America last week, Borderlands 2 boasts a 58-hour campaign that will take players to previously unseen regions of the planet Pandora.
A number of special editions are available, including the Borderlands 2 Deluxe Vault Hunter's Collector's Edition and the Ultimate Loot Chest Limited Edition.
Copyright: 2K GamesGearbox Software recently launched the Borderlands 2 skill tree builder website, enabling players to customise their characters before entering the game.
It will be supported with at least four campaign add-ons between September 2012 and June 2013.
The packs will cost $9.99 (£6.30) on PC and PS3 and 800 Microsoft Points (£6.80/$10) on the Xbox 360.
The DLC can also be purchased as part of a discounted Season Pass, which can be picked up for $29.99 (£18.90) on PS3 and PC, and 2400 Microsoft Points (£20/$30) on Xbox 360.
> Read Digital Spy's Borderlands 2 review
Watch a trailer for Borderlands 2 below: