Abstract: Based on the panel data of 110 prefecture-level cities in the Yangtze River Economic Belt (YREB) from 2011 to 2021, an index system for measuring the level of digital economy and common prosperity was constructed in this study. The econometrics and spatial statistics methods were used to analyze the impact of digital economy on common prosperity and the temporal and spatial characteristics. The results showed that: (1) The development of digital economy and common prosperity in the YREB showed an overall upward trend, but the development gap was gradually widening. The level of digital economy in the three regions was downstream > upstream > Middle stream, and the level of richness and common degree was downstream > middle stream > upstream; (2) The digital economy could significantly promote the level of affluence and commonality through increasing the entrepreneurial activity, but the promotion effect had obvious regional heterogeneity. The digital economy in the downstream region had the most significant improvement in the level of affluence, and the digital economy in the upstream region had the most significant improvement in the level of commonality. The release effect of digital dividend on the level of common degree was in a need to reach a certain level of affluence; (3) The effect of digital economy on affluence and commonality was the strongest in the downstream region. The clustering patterns of the influence coefficients of various cities varied. The spatial scalability showed a northeast-southwest trend.