Administrative unit proliferation carries significant policy consequences and has attracted considerable scholarly attention. Existing studies focus mainly on presidential systems, leaving a gap in understanding the causes of unit proliferation in other institutional settings. We argue that in parliamentary systems, electoral motives matter as in presidential systems, but proliferation decisions also depend on government type. Single-party governments are more likely to pursue proliferation to secure electoral success, especially under electoral uncertainty. Under dominant party systems with less uncertainty, such proliferation becomes less likely. Coalition governments face greater challenges due to ambiguity in policy responsibility and credit attribution, adding uncertainty to unit proliferation. Using original district-level splits data in Turkey from 1960–2018, we conduct random intercept logistic regression models to test these expectations. The results confirm that electoral motives and government type jointly shape proliferation decisions, adding to our understanding of how political institutions influence territorial policies. The study also assesses district level characteristics identified in prior work but situates them within the constraints of parliamentary systems. Taken together, the evidence shows how elite bargaining and electoral incentives structure territorial reforms in a context marked by electoral uncertainty, patronage, and various party systems.