Background Obsessive-compulsive disorder (OCD) is classified by the World Health Organization as 1 of the 10 most disabling conditions. However, nationally representative epidemiological data on OCD are not yet available in China. Aims To investigate the prevalence, comorbidity, role impairment and healthcare utilisation of OCD in China. Methods The present study used a multistage clustered area probability sample to obtain representative population-based data of adults from 157 nationwide disease surveillance points across 31 provinces in China. Trained interviewers conducted face-to-face interviews with respondents to collect information based on the Composite International Diagnostic Interview 3.0. Data weighting was performed to account for differential selection probabilities and response rates, and to post-stratify the sample to ensure its representativeness of the population in China. Results A total of 28 140 respondents (12 537 (44.55%) males and 15 603 (55.45%) females) completed the diagnostic interview. Two-thirds of the respondents with lifetime OCD had comorbid mental disorders, with OCD typically emerging later than the comorbidities. The most common comorbidities were mood disorders (39.67%, odds ratio (OR): 9.60, 95% confidence interval (CI 7.35 to 12.53) and anxiety disorders (32.75%, OR: 13.33, 95% CI 10.14 to 17.52). Overall, 588 (weighted 58.19%) respondents with obsessions or compulsions experienced role impairment, which was most severe in those reporting unspecified symptoms. Only 46 (6.74%) respondents with lifetime OCD and 28 (6.48%) with 12-month OCD received any healthcare services for their conditions. Conclusions The weighted lifetime and 12-month prevalence of OCD were 2.43% and 1.63%, respectively. Most patients with OCD reported comorbid mental disorders and role impairment, but very few sought healthcare services. National programmes to expand service coverage and increase awareness of OCD are essential to meet healthcare needs in China.