Nintendo of America boss Reggie Fils-Aime told Time that the system had sold 2.37m units in eight months, beating the DS's first year sales.
Fils-Aime attributed numerous factors, including recent Mario releases Super Mario 3D Land and Mario Kart 7, for its healthy sales.
"3DS has been having positive momentum since the digital content came on board with the eShop, the launch of Ocarina of Time and obviously the price reduction," he said.
"We've been able to fuel that fire with Pokemon: Rumble Blast and Star Fox. What Mario did was bring a whole new range of consumers into the 3DS franchise."
It was added that Legend of Zelda: Skyward Sword has become the fastest-selling release in the series in the US.
The 3DS will receive the Circle Pad Pro peripheral in January alongside horror adventure Resident Evil Revelations.
Nintendo 3DS will also see a firmware update adding 3D video recording and new StreetPass content next month.