How the “Absorption Processes” of Urban Innovation Contribute to Sustainable Development—A Fussy Set Qualitative Comparative Analysis Based on Seventy-Two Cities in China

The goals and transformation of sustainable urban development require fundamental innovation; however, urban innovation is a cyclical process, the paradigm of innovation itself needs to be dramatically transformed, and all innovation key elements need to be coordinated with each other to achieve sustainable urban outputs. Based on this, this paper uses the absorptive capacity theory to construct a model of the relationships between the acquisition dimension, digestion dimension, conversion dimension, utilization dimension, and sustainable development in the innovation process of smart cities and uses the fuzzy set qualitative comparative analysis (FSQCA) method to investigate the configuration mechanism in depth to show how the innovation process of these cities affects their sustainable development, taking the top 72 cities in China in terms of innovation capacity in 2020 as the research objects. The results of the study form three complex configuration paths that affect sustainable urban development, centered on the transformation of technological achievements, innovation management drive, and smart cities, and reveal that the economic and market foundations as the dimensions of urban innovation acquisition are not the core conditions for sustainable urban development. Based on this, this study develops a configuration classification for innovative cities that can achieve sustainable development, i.e., industrial paths, governance paths, and technology paths, and proposes strategic directions for sustainable urban innovation development.