Urban river-lake interfaces are crucial areas for substance migration and transformation, and prone to algal blooms. However, the phosphorus (P) cycle in urban river-lake interfaces has not been comprehensively investigated, especially for the mineralization and solubilization processes of phosphorus driven by phosphorus-solubilizing bacteria (PSB). In this study, we investigated the distribution characteristics of PSB, including inorganic P solubilization bacteria (IPB) and organic P mineralization bacteria (OPB), along the river-estuary-lake continuums of typical urban river-lake interfaces in Taihu Lake, China. Results showed that the concentrations of relatively recalcitrant P fractions (Ca-IP and OP) in sediments did not increase, but Fe/Al-IP increased significantly along the river-estuary-lake continuums. Though the community diversity and structure of both OPB and IPB showed insignificant differences along the continuums, their assembly mechanisms and ecological roles varied obviously among three regions. PSB communities presented the highest deterministic assembly process in estuaries (41-47%), with the homogenous selection 2-7% higher than that of total bacteria. Co-occurrence network analysis revealed that PSB played a significantly increasing role in keeping module connectivity along the continuums, and accounted for the community stability in estuaries via the highest negative co-occurrence pattern (53%). Besides, the proportion of single OPB in PSB was much higher in estuaries and the lake than that in rivers. The average abundance of OP mineralization genes increased along the typical continuum, but IP solubilization genes was highest in estuaries, followed by rivers. The results suggested varied PSB-mediated P transformation processes along the continuums, with rivers dominated by IP solubilization, estuaries enhanced by both IP solubilization and OP mineralization, and the lake enhanced by OP mineralization. Mantel test, PLS-SEM and machine-learning models elucidated that velocity, wNH4+and sTOC were probably the primary factors affecting PSB community and P fractions in urban river-lake interfaces. These findings provided a new insight for understanding P cycle in urban river-lake interfaces.