Population aging has indeed emerged as a significant challenge for China. Using data from four waves of the China Family Panel Studies, this paper explores the impact of population aging on household carbon emissions and its underlying mechanisms. Results show that population aging significantly decreases per capita household carbon emissions, and this conclusion is robust with respect to sample selection, measurement of primary independent variable, and data selection. Population aging influences household carbon emissions through negative consumption effects and positive composition effects, with the former playing a dominant role. Notably, population aging increases per capita household carbon emissions in items such as medicine, heating, and healthcare, while decreasing emissions in most other items. Furthermore, empirical evidence suggests impact heterogeneity across hukou, income level, and the health status of household head. The insights presented in this paper are crucial for advancing our understanding of sustainable development.