The research firm IDC said China will account for 26.5 percent of all smartphone shipments in 2012, compared to 17.8 percent for the United States.
"Looking ahead, the PRC smartphone market will continue to be lifted by the sub-$200 Android segment," said Wong Teck-Zhung, senior analyst at IDC.
"Near-term prices in the low-end segment will come down to $100 and below as competition for market share intensifies among smartphone vendors."
IDC said the move to 4G, or faster mobile networks, is another major growth catalyst and that growth is continuing in virtually all markets.
"The fact that China will overtake the United States in smartphone shipments does not mean that the US smartphone market is grinding to a halt," said IDC's Ramon Llamas.
"Now that smartphones represent the majority of mobile phone shipments, growth is expected to continue, but at a slower pace. There is still a market for first-time users as well as thriving upgrade opportunities."
IDC said it sees strong growth in India, which has the lowest smartphone penetration in the Asia region as operators roll out more affordable data plans and generous subsidies, and that it would be the third largest market by 2016.
A separate survey this week said smartphones are set to make up a majority of the global handset market next year, fueled by surging demand from consumers in both wealthy and emerging nations.