<p>Urban agglomerations are central to China’s development strategy, but technological progress does not always improve environmental and social outcomes. Understanding whether innovation and sustainability advance together is therefore critical for regional policy. Here we analyse sustainable development and technological innovation across 33 districts and counties in the Central Guizhou Urban Agglomeration, China, using panel data from 2013 to 2022 and a coupled coordination model. We find persistently low levels of both innovation and sustainability, pronounced spatial disparities, and weak coordination between the two. Although the influence of technological innovation has strengthened over time, its contribution to sustainable development remains limited. Urbanisation and economic growth are the dominant forces shaping this relationship, highlighting persistent tensions between innovation-led development and long-term environmental and social goals. These findings show the need to align innovation policy more closely with sustainability objectives in rapidly urbanising regions.</p><p></p>