Objectives: This study examined the subjective oral health and mental health of adults and assessed their effects on oral healthrelated quality of life. Methods: A total of 228 adults residing in Busan and Gyeongnam participated in a self-administered survey. The variables examined included subjective oral health, mental health, and oral health-related quality of life. Data were analyzed using t-tests, ANOVA, Pearson’s correlation analysis, and multiple linear regression analysis. Results: Oral health-related quality of life was significantly higher in females than in males (p<0.05). By occupation, professional and technical workers, as well as public and office workers, exhibited significantly higher quality of life compared to agricultural, forestry, and fishery workers (p<0.05). Periodontal health, xerostomia, chewing ability, dental health, cognitive function, and social support showed a positive correlation with oral health-related quality of life, whereas depression showed a negative correlation (p<0.01). The strongest predictor of oral health-related quality of life was depression (β=−0.301, p<0.001), followed by chewing ability (β=0.291, p<0.001) and periodontal health (β=0.191, p<0.003). Conclusions: To enhance the oral health-related quality of life in adults, dental treatments should be integrated with mental health promotion services aimed at addressing depression. Furthermore, institutional policies ought to support lifecycle oral care programs that prioritize the preservation of masticatory function and the prevention of periodontal disease.