While inadequate oral health has been linked to adverse mental health outcomes, there is limited understanding of such implications among refugees who bear a disproportionate burden of oral health disparities. This study aims to examine the effect of self-rated oral health on depression, anxiety, and stress among Syrian refugee parents resettled in Ontario. In this cross-sectional study, a total of 540 Syrian refugee parents who resided in Ontario for an average of 4 years and had at least one child under 18 years old were interviewed between March 2021 and March 2022. Information about self-rated oral health was gathered based on the question “In general, how would you rate the health of your teeth and mouth”. Responses ranged from 1 representing “excellent” and 5 representing “very poor”. The mean score (SD) of self-rated oral health was 3.2 (1.2). Mental health outcomes of depression, anxiety, and stress were measured using the Depression Anxiety Stress Scales (DASS-21). Multiple linear regression analyses were performed to assess the independent relationship between self-rated oral health and depression, anxiety, and stress, adjusting for other variables including, sociodemographic-, migration-, and health-related factors. Among participants, 6.3% rated their oral health as excellent, 26.9% as good, 23.1% as fair, 24.8% as poor, and 18.7% as very poor. Results of the multiple linear regression analyses indicated that poorer self-rated oral health was significantly associated with higher levels of depression (Adjβ = 0.98; p = 0.002; 95% CI = 0.38–1.59), anxiety (Adjβ = 1.03; p< 0.001; 95% CI = 0.54–1.52), and stress (Adjβ = 1.25; p< 0.001; 95% CI = 0.61–1.88). Further efforts and targeted interventions are needed to address the unmet oral health needs of Syrian refugees to improve mental health outcomes within this vulnerable population.