Background: Among the nursing aides employed at long-term care facilities (LTCFs), those with musculoskeletal disorders (MSDs) are most likely to experience disability or develop an intention to leave. The purpose of this study was to investigate the association of work-related psychological factors among nursing aides in LTCFs with MSDs in Taiwan. Methods: Purposive sampling was used in this cross-sectional study to enrol 308 nursing aides from residential LTCFs in Taiwan as research subjects. A demographic and job background survey, a job content questionnaire (JCQ), and the Nordic musculoskeletal questionnaire (NMQ) were used to collect data. Results: Lower job control associated with higher psychological job demands, and lower social support was associated with more severe MSDs for the nursing aides (p < 0.001). Among the MSDs reported by nursing aides in LTCFs, lower back pain was the most serious. In addition, nationality, age, exercise habits, chronic diseases, worksite, lack of rest time, lack of assistive devices, low coworker support, and high psychological job demands were significant factors affecting MSDs. In total, 42.1% of the variance in MSDs among nursing aides in LTCFs was explained. Conclusions: Work-related psychological factors among nursing aides in LTCFs have an important association with MSDs. For nursing aides, coworker support should be improved, and their psychological demands at work should be reduced.