Industrialization and urbanization are significant facets of modernization. The asynchronous development of the two is closely related to the agglomeration of producer services. This paper constructed an asynchrony index to describe the development gap between industrialization and urbanization. Various spatial weight matrices were introduced to test the spatial autocorrelation of the asynchrony index. Applying spatial econometric models, we explored the impact of agglomeration of producer services on the asynchrony index from two aspects: diversified agglomeration (DA) and specialized agglomeration (SA). The following conclusions are drawn from the empirical findings, which are based on data from 31 Chinese provinces between 2008 and 2019: (1) the asynchrony of industrialization and urbanization exhibits the spatial autocorrelation increasing over time; (2) SA exacerbates the asynchrony, while DA alleviates the asynchrony; (3) SA exerts greater impacts in highly industrialized and urbanized regions, while DA exerts greater effects in lowly industrialized and urbanized regions; and (4) agricultural dependence and infrastructure level weaken the impacts of SA and strengthen the impacts of DA. Income level weakens the impacts of both SA and DA. The results of this study provide a reference for policymakers to adjust the industrial layout in a targeted manner to regulate the asynchronous nature of modernization development.