Background <p>Cognitive function and psychological factors influence oral health-related quality of life (OHRQoL), but their effects on specific OHRQoL dimensions remain unclear. This study investigated the associations between cognitive function, individual and combined psychological symptoms, and four dimensions of OHRQoL among Myanmar adults.</p> Methods <p>A cross-sectional survey was conducted at a township health center in Yangon between February 2023 and May 2024. Data were collected using the validated Oral Health Impact Profile-14, Mini-Mental State Examination, and Depression, Anxiety, and Stress (DAS) Scale. Bivariate and linear regression analyses were performed.</p> Results <p>Among 316 participants, 49.4% had cognitive impairment, 33.5% anxiety, 22.8% depressive, and 13.3% stress symptoms. Stress was more common in males (<i>p</i> = 0.028), and cognitive impairment was more common in older adults (<i>p</i> &lt; 0.001). Males and older adults were more likely to experience multiple psychological symptoms. Females and older adults reported poorer oral function and orofacial appearance within OHRQoL dimensions. Cognitive impairment and psychological symptoms were associated with poorer overall and dimensional OHRQoL. All psychological symptoms remained independently associated with poorer OHRQoL and its dimensions after adjusting for confounders, while cognitive function remained significantly related only to oral function. The combined DAS model indicated that OHRQoL worsened with increasing numbers of psychological symptoms, highlighting their cumulative effects.</p> Conclusion <p>Cognitive impairment is associated mainly with oral function, while psychological symptoms demonstrate substantial and cumulative effects across OHRQoL dimensions. Enhancing oral function in individuals with cognitive decline and integrating mental health screening and education into dental care may improve oral and overall well-being.</p>