<p>In urban agglomerations, economic integration is closely linked to the digital economy, fostering economic, social, environmental, and sustainable development. However, the interrelationship between these two aspects has not been thoroughly examined. This paper addresses this gap by constructing a theoretical framework for economic integration and the digital economy in urban agglomerations. Using China’s Yangtze River Delta urban agglomeration (YRD-UA) as a case, we analyze its development status and interrelationship using the entropy weight method and canonical correlation analysis while identifying key influencing factors. Spatial autocorrelation analysis is also employed to examine spatial characteristics, spatial correlations, and specific countermeasures. Results indicate that: (1) Economic integration in the YRD-UA is gradually increasing while the digital economy experiences initial slow growth followed by acceleration; (2) Economic integration and the digital economy reinforce each other, with digital economy growth driving urban agglomeration optimization; (3) Both show positive spatial correlation; (4) Economic integration exhibits a positive spatial correlation with the digital economy, and spatial agglomeration is rising overall. Innovations of this study include: (1) Constructing and validating a theoretical framework to examine the interplay between economic integration and the digital economy within urban agglomerations; (2) Enriching this framework from the perspective of human resource mobility; (3) Identifying new pathways for mutual reinforcement based on urban agglomeration spatial structure.</p>