The digital economy serves as a catalyst for global economic growth, making its interaction with carbon emissions critical for sustainable development and green transformation. Using panel data from 110 cities in the Yangtze River Economic Belt from 2012 to 2021, this study evaluates DE and CE levels through the entropy weight TOPSIS method and analyzes their coupling and influencing factors via the coupling coordination and the diamond model. Results indicate that, first, DE and CE exhibit similar spatiotemporal evolution, characterized by annual growth and significant regional disparities. The downstream region grows 6% faster than the overall study area, while the CE growth rate in the midstream region is 7% higher. Second, coupling coordination has been improved, with low-coupling and micro-imbalanced regions as the dominant types. Notably, the upstream region records the fastest coupling coordination degree growth, reaching 9%. Finally, innovation, government policies, and environmental pressures are identified as the main drivers of spatial coordination, with innovation exerting the most extensive influence. This study yields actionable insights into DE-CE dynamics and provides valuable guidance for sustainable development strategies at both regional and global scales.