The spatial structure of urban agglomerations (SSUA) has been shown to substantially influence low-carbon development (LCD). To examine the impact of SSUA on LCD, in this study, SSUA was comprehensively measured using concentration, coupling coordination, and centrality. This was followed by an evaluation of LCD considering multiple related criteria and their interactions. Finally, the impact of SSUA on LCD was analyzed using a two-way fixed effects model and a geographically and temporally weighted regression model. Based on data from 17 urban agglomerations (UAs) in China, the following results were obtained: (1) UAs in southeastern coastal areas typically exhibit superior LCD performance (0.138-0.279) compared to UAs in China's northwest (0.129-0.203). (2) A one-unit increase in concentration is associated with a 0.262-unit increase in LCD, while a one-unit increase in coupling coordination is associated with a 0.007-unit increase in LCD. (3) In most UAs, centrality had a more variable impact, evolving from positive to negative, and then back to positive. These findings inform urban planning strategies for LCD across diverse UAs.