Objectives The study aims to explore the existing pattern of mental healthcare-seeking behavior among the adult population in Bangladesh, and to delineate the factors that influence the mental health patients' decision to receive mental healthcare services.Methods We used the National Mental Health Survey Bangladesh 2019 dataset with 7270 households to identify the patterns and catalysts of seeking mental health care services. A Probit model using a standard normal cumulative distribution function (CDF) with three specifications has been applied to identify the factors influencing mental healthcare-seeking behavior and the probability of seeking mental healthcare services in Bangladesh.Results We found that about 19% of the total adult population have mental health disorder in the country. Among the mental health disorder patients, only 10% seek healthcare services from different sources of mental healthcare services. Patients with addictive disorder show the lowest interest in seeking healthcare services, while patients with bipolar-related disorder receive treatment from mental healthcare sources. Findings portray that 4.8% of addictive disorder patients seek healthcare services. On the other hand, 34.4% of bipolar-related disorder patients receive treatment for mental health. In addition, the findings from the Probit model show that only the existence of other mentally disordered family members is the only statistically significant determinant among the socio-economic factors, such as gender, age, religion, education level and residential status. The marginal effects analysis shows that the existence of mentally disordered family members increases the probability of seeking mental health care services by around 6%. The other socio-economic variables considered in the study are found statistically insignificant. However, a married woman has a significantly higher likelihood of seeking treatment than an unmarried woman, while the family size is the only variable that significantly influences treatment-seeking behavior for men.Conclusion Though mental health conditions are major public health concerns in Bangladesh, the treatment-seeking behavior among the mentally diorder people is very low, implying a large treatment gap in the mental health sector. The findings indicate the urgent need to increase mental health service coverage among mental health patients.