The ecological environment of urban water resources in the Yangtze River Economic Belt (YREB) is in a huge challenge; yet, while myriad studies have investigated the carrying capacity or sustainable utilization of Chinese water resources, few to none have looked at the inclusive sustainable development of water resources. In this article, a new concept of urban water inclusive sustainability (UWIS) is firstly proposed, and the conceptual framework of ASFII and a five-dimensional indicator system are developed, integrating availability, sustainability, friendliness, inclusiveness and innovation. The panel data of 38 cities in the YREB are adopted from 2008 to 2018 to measure UWIS and five development indexes by the TOPSIS (technique for order preference by similarity to ideal solution) and entropy method. Moreover, the characteristics of the temporal–spatial evolution of the overall system and subsystems coupling coordination are described using the coupling coordination degree model. Key factors that hinder UWIS are identified through the obstacle degree model. The results indicate that the overall UWIS showed a gradual upward trend at a lower to medium level from 2008 to 2018 and a friendliness > sustainability > inclusiveness > innovation > availability index. The UWIS from high to low is YRDUA (Yangtze River Delta urban agglomeration), MRYRUA (middle reaches of the Yangtze River urban agglomeration) and CCUA (Chengdu–Chongqing urban agglomeration). The 38 cities are in low-level coordination, and their temporal characteristics show a trend of economy > science and technology > water resources > environment > societal system, YRDUA > MRYRUA > CCUA. The spatial differentiation is manifested as high in the east and low in the west. The main obstacles come from 12 factors, such as the water resources utilization rate, etc. The findings of our study will be a scientific reference for the Chinese government to track UWIS and ensure urban water resources security in the YREB.

Megacities in the Yangtze River Economic Belt (YREB) are facing severe challenges and unbalanced development. Combating megacity syndrome is crucial for achieving modernization. This study developed a Development-Autonomy-Inclusiveness governance framework to characterize megacity governance capacity modernization (MGCM). The integrated model is employed to evaluate the MGCM for nine megacities along the YREB in China from 2013 to 2022. The key determinants are identified by Geo-detector. The configuration pathways and synergistic mechanisms for high MGCM are depicted using fsQCA. The empirical study indicates that: (1) The MGCM is at a low level but displays a slight upward trend, with development capacity > autonomy capacity > inclusiveness capacity. The MGCMs of three urban agglomerations manifest as being development-driven, autonomy-constrained, and autonomy-promoted. (2) The synergistic interaction among determinants is greater than any single factor. (3) Megacities exhibited distinct pathways to achieve high MGCM: tri-capacity synergy pattern in the Yangtze River Delta, development dominant pattern in Chengdu-Chongqing, autonomy weakness pattern in the Mid-Yangtze River, and adversity survival pattern during extraordinary periods. A novel theoretical framework and practical examples are proposed for boosting the modernization of governance capacity in China’s megacities, offering valuable insights for advancing the governance modernization of megacities worldwide.