Purpose: This study investigated the mediating effect of depression on the relationship between physical symptoms and sleep quality among older adults. Method: A total of 178 community-dwelling older adults participated in the study. Data were collected from October 2 to 20, 2024, using self-report questionnaires, and analyzed using the t-test, one-way ANOVA, Scheffe’s test, and Pearson’s correlation coefficients with SPSS Statistics. Mediation analysis was performed using Hayes’s PROCESS macro model 4 and bootstrapping methods. Results: Sleep quality was found to have a significant negative correlation with both physical symptoms and depression. In addition, depression showed a significant positive correlation with physical symptoms. Depression was found to mediate the relationship between physical symptoms and sleep quality. Conclusion: This study indicates that depression is a significant mediator in physical symptoms and sleep quality, which suggests that, to improve older adults’ sleep quality, psychosocial factors, such as depression, must be considered alongside physical symptoms. Therefore, an integrated health management strategy that addresses both physical and psychological factors is necessary to effectively enhance sleep quality in older adults.