Abstract Background Despite the sharp rise in antidepressant use, the underutilization of mental healthcare services for depression remains a concern. We investigated factors associated with the underutilization of mental health services for potential depression symptoms in the Republic of Korea, using a nationally representative sample. Methods Data were obtained from the Community Health Survey (2011–2012) conducted in the Republic of Korea. Participants comprised adults who reported potential depression symptoms during the year prior to the study (n = 21,644); information on professional mental healthcare use for their symptoms was obtained. The association of demographic, socioeconomic, and health-related factors with consultation use was analysed via multiple logistic regression. Adjusted odds ratio and 95 % confidence intervals were estimated. Results Among those reporting potential depression symptoms, only 17.4 % had consulted a medical/mental health professional. Elderly individuals of both genders had significantly lower consultation rates compared to middle-aged individuals. Unmet healthcare needs and a history of diabetes mellitus were associated with lower consultation rates. After stratification by age, elderly individuals with the lowest education and income level were significantly less likely to seek professional mental health services. Married, separated, or divorced men had lower consultation rates compared to unmarried individuals, whereas married, separated, or divorced women had higher rates. Conclusions The results suggest that target strategies for vulnerable groups identified in this study—including elderly individuals—need to be established at the community level, including strengthening social networks and spreading awareness to reduce the social stigma of depression.