The most tangible impact of the digital transformation of urban governance lies in the creation and innovation of standout application scenarios. Using content analyses of 103 cases from the Blue Book on Application Scenarios for the Digital Transformation of Urban Governance in China, this study reveals the problem domains, the technological applications, and the performance improvements in building application scenarios for digital transformation in mega-city governance. The findings indicate that, among the practicalities addressed by these scenarios, the most prominent are the “Efficiently Accomplish One Thing” issue and the “Efficiently Manage One Thing” issue. The key domains include smart governance, intelligent transportation, smart communities, and smart urban management, while areas such as smart environmental protection and intelligent security receive relatively less attention. Collaboration between governments and enterprises emerges as the most common approach in scenario development; however, the importance of citizen co-production and think tank participation is gradually increasing. Diverse technological applications are evident, with a focus on artificial intelligence and IoT-based sensing and monitoring technologies. These technologies are applied across the infrastructure, functional, and application layers, emphasizing the synergistic effects of different technology combinations to deliver comprehensive solutions for urban governance challenges. The application scenario development in existing cases has achieved performance improvements across the economic, efficiency, effectiveness, and equity dimensions. This study extends the discussion of digital transformation in urban governance from macro-level strategies to micro-level application scenarios, offering insights for mega-cities on selecting scenarios to achieve high-efficiency digital transformation.