The advancement of Chinese-style modernization and construction largely hinges on urban‒rural integrated development (URID) within the Yangtze River Delta region (YRDR). An index system for evaluating urban‒rural integrated development, encompassing economic, social, and quality-of-life dimensions, is formulated in this study. This study examines the degree of URID and its determinants across 41 cities within the YRDR during the period spanning from 2012 to 2021 by employing the entropy weighting method and geodetic detector model. The results reveal the following. First, the overall URID in the YRDR accelerated. Cities in the central and eastern parts exhibit a greater URID, which decreases toward the west, north, and south, highlighting prominent developmental imbalances between cities. Second, integrated economic development between urban and rural areas (URAs) has consistently demonstrated superior performance. Social integration in URA has exhibited a steady upward trajectory, whereas the integration and improvement of urban and rural residents' quality of life have advanced at a comparatively modest pace. Third, the factors that significantly influence the URID within the YRDR include per capita GDP, postal and telecommunication services per capita, and the proportion of private car ownership. Conversely, the impact of governmental intervention and agricultural security appears to be comparatively diminished. Moreover, the combined influence of interacting dual factors surpasses that of individual elements, with the influence gradually stabilizing over time. Ultimately, this study provides policy suggestions to foster integrated urban and rural development in the Yangtze River Delta (YRD) with a focus on regional collaboration and development strategies.