Carbon emission efficiency is vital for environmental performance, and the digital economy, as an emerging force, plays a critical role in enhancing carbon emission efficiency. This study employed panel data from 30 Chinese provinces (2010–2020) to measure the digital economy index and carbon emission efficiency through Principal Component Analysis and the Super-Efficiency SBM model. A double fixed effects model was applied for regression, followed by robustness tests, heterogeneity analysis, and an investigation into the mechanisms and spatial spillover effects. Five findings are elicited: (1) Spatiotemporal distribution differences exist between digital economy level and carbon emission efficiency. (2) The digital economy effectively enhances carbon emission efficiency, a result that remains robust after endogenous and robustness tests. (3) Significant spatial spillover effects are observed, where improvements in the digital economy enhance carbon emission efficiency in neighboring areas. (4) The impact of the digital economy is more pronounced in eastern and high digital development regions but weaker in the northeastern and low digital development areas. (5) The main pathways through which the digital economy influences carbon emission efficiency are industrial structure upgrading, energy structure optimization, and green technological innovation. These findings extend the environmental benefits of the digital economy, providing insights for achieving the dual carbon goals.