The platform holder will instead focus on smaller, localised promotions and experiences, Major Nelson has revealed.
"As you saw at E3, we have a solid line-up of games launching this holiday, along with other entertainment experiences," writes Major Nelson.
"We've changed our approach a little, though. This year, Xbox will be focusing on smaller, more localised promotions and experiences for press, partners, retailers and customers around the world.
"Which means that as you might have seen on some of the news sites today, we won't be taking part in gamescom or Tokyo Game Show this year."
He concludes: "Both are still important shows for the industry, and we do wish the organisers well."
Microsoft's E3 press conference included games such as Halo 4 and Gears of War: Judgement.
It also unveiled SmartGlass, which links the Xbox 360 with tablets and smartphones, offering supplementary materials and new gameplay features.
This year's gamescom event takes place in August. The Tokyo Game Show, meanwhile, runs from September 20 to 23.
Watch a SmartGlass demo video below: