<p>This study analyses 1870 pairs of party secretaries and mayors in prefecture-level cities from 1993 to 2020 to examine how leader team configurations affect mayors’ career development. It focuses on the roles of seniority, capability, and relationships between leaders. Results show that mayors’ career advancement is more likely when the party secretary has greater seniority—such as longer party tenure, earlier office assumption, or local origin—especially if the mayor is from another city. Comparable capabilities between the two leaders reduce the mayor’s career prospects, while differences in their relationship have a non-significant impact. This research contributes empirical evidence highlighting the importance of seniority and capability in leader team configurations, suggesting that political parties should consider these factors to promote effective governance.</p>