This research examines how different political party systems influence the degree of bureaucratic politicization across states. Drawing on a mixed-methods design, it features cross- national statistical analysis using two OLS regression models based on the Quality of Government Expert Survey data, followed by qualitative case studies of Germany, Turkey, and Bosnia and Herzegovina. The results demonstrate that multi-party systems are associated with lower levels of bureaucratic politicization, whereas two-party and dominant-party systems exhibit higher politicization. Furthermore, within multi-party systems, coalition stability and structure critically mediate the degree of bureaucratic politicization. Case study findings determine distinct pathways of politicization, with centralized executive-driven mechanisms in Turkey and fragmented, party-distribution mechanisms in Bosnia and Herzegovina. Germany’s coalition dynamics, by contrast, demonstrate how formalized power-sharing arrangements can reinforce bureaucratic neutrality. Collectively, these findings underscore the importance of moving beyond bureaucratic structures to consider how party systems and coalition dynamics shape administrative autonomy and neutrality.