Limited research has been conducted on strategies to improve the efficiency of HIV services for key populations (KPs). This study investigates ways to enhance healthcare delivery efficiency, focusing on HIV services for KPs. We explore two strategies: expanding service volume and offering multiple HIV services within a single health facility. Using data from the Linkages Across the Continuum of HIV Services for Key Populations Affected by HIV (LINKAGES) program in Kenya and Malawi, we exploit the variation in services provided to assess correlations between different service delivery configurations and their costs. We apply log-log fixed-effects regression models to analyze relationships between the total costs of four HIV services and the volume and range of services delivered. We find that service volume increases correlate with higher total costs, albeit less than proportionally, consistent with possible economies of scale. Negative correlations between service integration and total costs suggest that integrating HIV services for KPs could lead to reduced total costs for some service combinations. These results indicate potential strategies to increase the efficiency of HIV services for KPs, which can inform strategic planning and program execution in Kenya, Malawi, and similar countries.