Thailand is expected to be among the worst-hit countries in the region
The World Bank has said economic growth in East Asia will slow sharply as the downturn saps demand for its exports.
The 10 countries, including China and Thailand, will grow by 5.3% this year, half of the growth seen in 2007, the World Bank said in a report.
China's economy is expected to grow by 6.5% in 2009, down from 13% in 2007.
But the organisation said China's huge stimulus package meant its economy should start to recover later this year, potentially boosting the region.
East Asia is expected to be among the worst hit areas by the global economic crisis, as richer nations in recession cut back on importing goods from the region.
"There is no doubt that the East Asia and Pacific region is confronting very difficult times," said Vikram Nehru, the World Bank's chief economist for the region.
Among the World Bank's forecasts, the biggest reversals were Thailand, which is expected to shrink by 2.7% after growing 4.9% in 2007, and Cambodia, predicted to contract 1% after growing by more than 10% two years ago.
As a result, the World Bank said it expects about 10 million more people in the region to stay below the poverty line as funding for poverty reduction is cut back.
The organisation said the effects of China's stimulus package - announced last November and worth about 4tn yuan ($586bn; £421bn) - are likely to begin this year and take "full hold in 2010, potentially contributing to the region's stabilisation, and perhaps recovery".