<p>Against the backdrop of the long-term entrenchment of high-carbon development pathways, identifying mechanisms for breaking carbon constraints is essential for advancing regional low-carbon transitions. Focusing on the Yangtze River Delta (YRD) urban agglomeration, this study develops a carbon unlocking level evaluation framework incorporating industrial, institutional, technological, and cultural dimensions. Carbon unlocking levels from 2012 to 2023 are measured, and intercity carbon unlocking level linkages are identified using a modified gravity model. Social network analysis is employed to reveal the spatial association network structure, while a temporal exponential random graph model (TERGM) is applied to examine the dynamic evolution of the network and its driving mechanisms. The findings are as follows: (1) The carbon unlocking level of the YRD exhibits a fluctuating upward trend, with pronounced heterogeneity across dimensions in evolutionary trajectories and spatial patterns. (2) Carbon-unlocked spatial correlation networks exhibit favourable connectivity, with increasing network density, yet overall redundancy remains low.(3) There is a pronounced functional division within the network, with the coexistence of primary overflow block, primary beneficiary block, and broker block; carbon unlocking spatial linkages occur primarily between modules, while intra-module cohesion remains relatively weak.(4) The evolution of the YRD network is driven not only by exogenous structural influences but also by endogenous self-organisation within the network itself. Reciprocity and transmissibility both exert positive influences on the formation of carbon unlocking networks, exhibiting notable stability. These findings contribute to deepening our understanding of collaborative mechanisms for regional low-carbon transition, while providing valuable reference for low-carbon governance and policy coordination at the urban cluster level.</p>