Background <p>Since South Korea entered a super-aged society in 2024, the demand for formal care services has increased rapidly. Formal care workers employed in hospitals and long-term care facilities, including long-term care aides and paid caregivers, play a central role in providing health-related care and assistance with daily living for older adults. Despite their essential contribution, empirical evidence on their working conditions and health remains limited and no dedicated cohort-based study focusing on this workforce currently exists. This study aimed to develop an integrated, cohort-based survey instrument to systematically assess the working conditions, care environments, and health of institution-based formal care workers in South Korea.</p> Methods <p>The survey instrument was developed through a multi-phase scale development process, which included: (1) a review of existing national and international labor and care-work surveys; (2) in-depth interviews with institution-based care workers employed in hospitals and long-term care facilities, followed by qualitative content analysis using Attribute Analysis of the Dynamic Mapping Method; (3) item generation, consolidation, and inter-researcher validation; (4) expert consultation to assess content validity; and (5) pilot testing with formal care workers. Qualitative findings and expert feedback were iteratively integrated to refine domains and survey items.</p> Results <p>The final conceptual framework comprised three major domains (i.e., sociodemographic characteristics, care work environment, and health), encompassing 11 subdomains and 79 variables. The finalized instrument consisted of 79 items encompassing multiple dimensions of institutional care work, including employment status, care-related workload, occupational health and safety, organizational and social support, and physical and mental health. Key components related to working conditions (including working hours and income), organizational support, and workplace safety were prioritized through expert review and importance assessment.</p> Conclusions <p>This study presented the first cohort-oriented survey instrument specifically designed for institution-based formal care workers in South Korea. By focusing on care labor within hospitals and long-term care facilities, the instrument provided a robust foundation for longitudinal monitoring, policy evaluation, and research on workforce sustainability in aging societies.</p>