Abstract: Promoting the construction of a zero-waste society is an important pathway to reduce solid waste pollution, alleviate resource constraints, and enhance ecological civilization, with significant practical significance in achieving harmonious coexistence between humans and nature. Based on data from 11 provinces and municipalities in the Yangtze River Economic Belt (YREB) from 2011 to 2020, an evaluation index system for a zero-waste society was constructed in five dimensions: solid waste reduction, solid waste recycling, solid waste harmless treatment, capacity building assurance, and public ecological awareness. Methods of subjective and objective weighting method, Dagum Gini coefficient, and QAP regression analysis were adopted to calculate and analyze the spatiotemporal differences in the zero-waste society of the YREB and its influencing factors. The results were as follows. (1) The zero-waste society level in the YREB showed a stable growth trend, but the overall level remained relatively low. Overall, the zero-waste society level in the YREB exhibited a spatial pattern of “downstream > upstream > midstream”. (2) From the perspective of subsystems, the level of solid waste reduction was the highest. The levels of solid waste recycling and harmless treatment were relatively high and showed an apparent increasing trend. The level of capacity building assurance experienced a significant growth in 2016 and remained stable thereafter. In general, the level of public ecological awareness was relatively stable. (3) The inter-regional differences in the zero-waste society of the YREB were the main cause of the overall differences. The differences between regions were specifically manifested in the significant spatial variations between downstream areas and other areas, with a certain tendency of expansion. (4) The key factors causing the spatially uneven development of zero-waste society in the YREB included the differences in regional openness, urbanization rate, population density, economic growth, industrial structure, and technological innovation.