The firm said in a press statement late Monday that its console outsold PS3 three-to-one on the day after Thanksgiving, a major shopping day in the U.S. that is marked by price reductions at retail.
Microsoft said unit sales were up 25 percent over Black Friday 2007, although the company did not provide hard numbers.
U.S. NPD data for November is due in the coming days.
Sony did not respond to the claim as of press time.
Don Mattrick, SVP of Microsoft's Interactive Entertainment Business said in the statement, "Record Black Friday sales in the U.S., coupled with our existing global install base of 25 million and an online community of more than 14 million Xbox LIVE members, have laid the groundwork for continued global sales momentum in 2009.”
Xbox 360's three-model line ranges from $199 for the hard drive-less Arcade model to the $399 120GB Xbox 360 Elite.
The firm also said that Xbox 360 console sales in Europe have increased week over week thanks to a September price drop. Sales have been "up as much as 400 percent, with sales nearly double year over year and reaching 7 million consoles sold this generation," the company said.
Rumors have been circulating suggesting that PS3 pricing would become more competitive around the end of Sony's current fiscal year in March 2009, although Sony Computer Entertainment America recently told Edge that it has "no plans" for such a price drop.
The standard Blu-ray-equipped 80GB PS3 model currently retails for $399 in the U.S.