The spatial agglomeration of specialized, refined, distinctive, and innovative (SRDI) enterprises has become an important feature of China’s innovation-driven development strategy. However, whether such agglomeration is associated with narrower or wider disparities in urban sustainable development remains unclear. Using an unbalanced panel of 296 Chinese prefecture-level cities from 2013 to 2024, this study constructs a city-level measure of SRDI enterprise agglomeration and examines its association with disparities in urban sustainable development. A two-way fixed-effects model is employed, supplemented by potential channel and heterogeneity analyses. The results show that SRDI enterprise agglomeration is significantly associated with greater city-level relative disparities in urban sustainable development. Further analysis suggests that nonagricultural industry development and innovation output may represent potential transmission channels underlying this positive association. Heterogeneity analysis reveals that this positive association is stronger in cities southeast of the Hu Huanyong Line, varies with proximity to innovation cores, and differs across population-density groups. These findings indicate that the spatial concentration of innovative enterprises may be associated with local development gains as well as more uneven development patterns across cities. The results highlight the importance of improving the capacity of less-advantaged cities to absorb and transform the benefits associated with SRDI enterprise agglomeration in order to achieve more balanced and sustainable urban development.

Growing uncertainty in the external environment has heightened concerns about supply chain security and resilience. Existing studies mainly examine the effects of China’s Specialized, Refined, Distinctive, and Innovative (SRDI) “Little Giant” certification on certified firms themselves, while its implications for the supply chain configuration of connected firms remain less understood. Using the staggered timing of certification, this study uses customer–supplier relationship data from Chinese listed firms over the period 2012–2025 and employs a staggered difference-in-differences model to examine whether downstream customer certification is associated with changes in supply chain diversification among upstream suppliers. The results show that “Little Giant” certification significantly reduces the concentration of upstream suppliers’ major trading relationships, leading to a more dispersed distribution of transaction shares across major partners. This finding remains stable across a range of alternative specifications, while an interaction-weighted event-study analysis provides complementary evidence on heterogeneous treatment timing and dynamic patterns. The mechanism analysis provides suggestive evidence consistent with a reputation-related channel and operating-resource adjustment: certified customers are associated with greater positive media exposure for their suppliers and higher operating working capital investment, while changes in current assets provide complementary evidence of operating-resource adjustment. Further analysis indicates that the estimated association is more evident in procurement relationships than in sales relationships, although the difference between the two estimates is not statistically significant. The estimated association also tends to be stronger among suppliers that exhibited overinvestment before certification and those with larger pre-certification market shares. These findings extend research on the economic consequences of SRDI certification from certified firms to their supply chain partners and suggest that firm-targeted industrial policy may be associated with cross-firm adjustments in major trading relationships through existing customer–supplier linkages.