Early adopters will receive a 10% discount, lowering the cost from £11.99 to £10.79.
Pre-purchasing the game also provides access to its final beta, which begins on August 14, ending at the game's launch.
To celebrate its imminent release, the entire Counter Strike franchise is on offer as part of Steam's Midweek Madness promotion.
Users can pick up Counter-Strike, Counter-Strike: Condition Zero, Counter-Strike: Source and Counter-Strike: Global Offensive in one package for £12.91, reduced from £37.96.
Counter Strike: Global Offensive will feature seven classic maps, five for the Bomb/Defuse mode and the other two for Hostage Rescue, with each map receiving graphical upgrades while leaving level layouts intact.
The game's beta launched earlier this year on PC for users who completed a survey through Steam.
It was originally due to feature cross-platform play, until the feature was pulled to make frequent post-release updates possible on PC.
Counter Strike: Global Offensive will be released on August 21 for Xbox Live Arcade, PSN, PC and Mac.
> Counter-Strike: Global Offensive interview - Valve on its latest game
> Counter-Strike: Global Offensive - Preview
Watch the Counter-Strike: Global Offensive trailer below: