The uneven proliferation of artificial intelligence (AI) presents unexamined challenges to sustainable regional development. This study provides robust empirical evidence on how the inter-city AI gap influences environmental dynamics, specifically via transboundary air pollution. Using a framework based on the Technological Gap Theory, the results demonstrate that a wider AI gap significantly intensifies air pollution transmission between cities. The primary mechanisms are widening disparities in digital infrastructure and imbalanced flows of capital and labor. This effect is context-dependent and most severe for economically underdeveloped cities, creating a new form of environmental inequity. The analysis further reveals that while environmental regulations can mitigate this negative impact, technology-centric policies lacking green synergy may amplify it. The research’s findings offer a new theoretical lens on techno-environmental inequality and underscore the necessity of synergistic policies that simultaneously bridge the digital and environmental divides to foster equitable and sustainable development.