Under the vision of the “dual carbon” targets, the digital economy and government governance have emerged as pivotal means for urban low-carbon transition. This study, based on theoretical analysis, utilizes panel data from 253 Chinese cities spanning 2011 to 2019 to investigate the relationship between the digital economy, government governance, and urban low-carbon transition. The findings demonstrate that: (1) The digital economy not only directly contributes to low-carbon transition but also exerts an indirect influence through enhancing labor productivity, accelerating green technological innovation, and upgrading industrial structures; (2) Significantly, government governance can synergize with the digital economy to propel urban low-carbon transition, this synergistic effect can be achieved through mechanisms related to green technological innovation and industrial upgrading; (3) Overall, the moderating effect of governance effectiveness is more significant than governance capability; (4) Analysis of heterogeneity reveals that first-tier cities, core cities, and cities in the central and western regions exhibit more efficient low-carbon transitions. These findings offer valuable theoretical insights and practical guidance for advancing urban low-carbon development and shaping relevant policy decisions.