The post-pandemic resurgence of the global wellness economy has placed unprecedented operational demands on Thailand’s massage and spa sector, a critical pillar of the nation's "Medical Hub" strategy. This study investigates the causal relationship between Human Resource Management (HRM) practices and operational efficiency within registered massage and spa establishments in Bangkok. Utilizing a quantitative research design, data were collected via a survey of 265 personnel selected through simple random sampling. The research framework evaluates eight distinct HRM dimensions—ranging from human resource planning and recruitment to safety protocols and organizational development—against four key metrics of operational efficiency: quality, quantity, time, and cost. The findings reveal a significant positive correlation between strategic HRM interventions and operational outcomes, identifying "Training and Development" and "Compensation Management" as the most potent predictors of efficiency. These results suggest that in a labor- intensive industry characterized by high turnover and a widening skills gap, investments in human capital are not merely supplementary but fundamental to sustaining service standards. This study contributes to the literature by quantifying the impact of HRM in the specific context of Bangkok's wellness sector, offering actionable insights for policymakers and business operators aiming to enhance competitiveness in the recovering tourism market.