Household air pollution from use of solid fuels such as coal and firewood for cooking is common in the developing world. Children under five years of age are likely to be particularly vulnerable. Yet relatively little attention has been paid to the contribution of household fuel transitions when attributing reasons for China's dramatic progress in reducing child mortality. This paper examines the effect of reducing household solid cooking fuel dependence on the under-5 child mortality rate in China. The results reveal that a percentage point decrease in the proportion of households cooking mainly with solid fuels has on average been associated with a reduction in the under-5 child mortality rate of about 10.1 per 100,000 live births, all else equal. We find that the reduction in the share of households cooking with solid fuels over 2000–2010 contributed about 12% of the reduction in the annual under-5 child mortality rate in China, helping to avoid about 39,000 deaths in 2010.