Public Service Malls (PSMs) are designed to integrate services from multiple agencies within a single service environment, yet physical co-location does not necessarily ensure organizational integration. This study examines how structural arrangements shape coordination and service integration in the Payakumbuh City Public Service Mall and provides an empirical diagnosis of organizational fragmentation underlying its operation. Using a qualitative single-case study design, data were collected through an in-depth semi-structured interview with the Coordinator of the Integrated Service Substance Sector of the Payakumbuh City Investment and One-Stop Integrated Service Office (DPMPTSP), non-participant observation, and analysis of organizational and cooperation documents. Data were analyzed through thematic coding across structural dimensions, including division of labor, authority distribution, coordination, formalization, communication, technological integration, human resources, and institutional support, supported by source triangulation. The findings indicate that the Payakumbuh City PSM has successfully improved physical accessibility through shared facilities, common front-office arrangements, and municipal support. However, participating agencies continue to retain their own mandates, procedures, personnel arrangements, and decision-making authority. DPMPTSP performs a coordinating role but lacks sufficient formal authority to harmonize substantive service procedures across agencies. As a result, coordination remains partly reactive, digital integration is limited, and staff rotation affects service continuity. The study concludes that the Payakumbuh City PSM demonstrates physical integration without equivalent organizational integration. Its contribution is not the development of a universal organizational-design model, but a case-based structural diagnosis showing how fragmented authority, agency-specific formalization, and limited integrative mechanisms constrain one-stop public service arrangements. The findings highlight that effective public service integration requires not only physical co-location but also aligned authority, procedures, technology, and human resources across institutional boundaries.