Background: Sleep disorder is a precursor to depression, which is one of the psychological factors associated with periodontal disease that, in turn, affects general and periodontal health. This study aimed to investigate the relationship between sleep duration, depression, and periodontitis in older people aged over 65 years. Methods: A total of 2,002 older adults aged 65 years or older were included in the study. Their general and health aspects, including smoking, drinking, diabetes, hypertension, and depression, were investigated. Periodontitis was examined using the Community Periodontal Index (CPI). Data were analyzed through a complex sampling design method. Frequency and crossover analyses were conducted to investigate the relationship between depression and periodontitis. To investigate the effect of depression on periodontitis, a logistic regression analysis was performed. Results: Regarding depression and participants' general characteristics, statistically significant differences were found in sex, economic activity, smoking habit, and CPI (p<0.05). In the presence of depression, the odds ratio for periodontitis was 1.84, and the adjusted odds ratio for age, sex, economic activity, residence type, household income, education level, smoking habit, drinking, hypertension, and diabetes was 1.72, representing a significant difference (p<0.05). Conclusion: This study examined the relationship between depression and periodontitis in older persons and confirmed a significant correlation. As the population of older adults increases, we should pay attention to their mental and oral health as well as systemic diseases. Various programs for the health promotion of older persons need to be implemented to improve the quality of life of older people.