Gears of War 3 sold over three million copies in its first week of availability, cementing its position as "the biggest game of 2011", according to publisher Microsoft.
The platform holder said its success has helped the series become the first Xbox 360 exclusive franchise to eclipse the $1 billion sales milestone.
Microsoft also said the game has garnered more than 50 perfect review scores and become the highest-rated Xbox 360 exclusive of the year.
"Gears of War was the first killer app for Xbox 360, and the series has continued to contribute directly to the overall success of the platform ever since," said Microsoft corporate vice president Phil Spencer.
"Gears of War 3 kicked off the biggest Christmas period in Xbox history, setting the standard for the kind of amazing, action-packed experiences gamers should expect on Xbox 360 this year."
The first Gears 3 DLC is set to feature Michael Barrick, lead character from of the Gears of War comic series, Epic design director Cliff Bleszinski said yesterday.