Abstract: Objectives: To test the hypotheses that: (1) Prevalence of periodontal disease would be higher in people with a history of psychosis when compared to the general population and (2) Demographic, life‐style related factors and co‐morbid medical conditions would predict periodontal disease in people experiencing psychosis. Methods: The authors performed cross‐sectional analysis of baseline data from the UK Biobank study (2007–2010), identifying cases with psychosis using clinical diagnosis, antipsychotic medication, and self‐report. Demographic (age, gender, ethnicity, socioeconomic status), lifestyle‐related(BMI, blood pressure, smoking and alcohol intake, physical activity) and physical co‐morbidities (cancer, cardiovascular, respiratory, inflammatory disease and metabolic conditions) were included as potential risk factors for periodontal disease among people with a history of psychosis using logistic regression analyses. The analysis sample included 502,505 participants. Results: Risk of periodontal disease was higher in people with psychosis, regardless of how cases were identified. Patients with a clinical diagnosis had the highest proportion of periodontal disease compared to the general population (21.3% vs. 14.8%, prevalence ratio 1.40, 95% CI: 1.26–1.56). Older and female cases were more likely to experience periodontal disease. Lifestyle factors (smoking) and comorbidities (cardiovascular, cancer or respiratory disease) were associated with periodontal disease among people with a history of psychosis. Conclusions: The findings suggest that periodontal disease is more common in people with a history of psychosis, compared to the general population. Prevention and early diagnosis of periodontal disease should be a priority for oral health promotion programmes, which should also address modifiable risk factors like smoking which also contribute to co‐morbid systemic disease.