The health concerns of marginalized social groups are frequently overlooked. The PhD project employs a mixed-method approach encompassing an examination of the health-seeking behavior of female sex workers by exploring their health vulnerabilities, and the influencing factors in South-western region of Bangladesh. A systematic review on the study topic was conducted to identify knowledge gaps in this field first. The findings of the systematic review indicated concerns regarding sexual and reproductive health (SRH) issues, lack of access and awareness, social stigma, non-SRH matters, and drugs, violence and abuse. The data collection for this explanatory mixed-method study comprised a survey of 384 female sex workers and in-depth interviews with 20 participants for data triangulation purposes. The data were gathered from four categories of female sex workers i.e. those operating in brothels, hotels, home locations, and on the streets, from designated regions in the Khulna, Jessore, and Satkhira districts of southwestern Bangladesh. The quantitative component of the study, involving a survey, was conducted initially, collecting data exclusively from female sex workers. Subsequently, six key sector workers were interviewed alongside 14 female sex workers during the qualitative phase of the study. The findings were integrated to build discussion, implications and conclusion of the research in the final stage. Our integrated findings reveal that female sex workers exhibited diverse healthcare-seeking behaviors shaped by socioeconomic, familial, and societal influences in Bangladesh. We noted that around one-third of the participants favoured government services, while two-thirds (64.1%) reported of recent health check-ups. However, factors like higher income, joint family structures, and experiences of abuse were associated with lower service utilization (p < 0.001). Female sex workers shared experiences of encountering substantial obstacles such as stigma, harassment, insufficient infrastructure, and a scarcity of affordable specialized care, which calls for the pressing necessity for targeted interventions, health system accountability, and customized services to meet their physical, mental, and reproductive health need. Findings of this study will aid researchers, program planners, and policymakers in developing or enhancing strategic interventions for this marginalized group. The results have been shared with the target audience such as female sex workers, pertinent NGOs, research communities and local health professionals. Two qualitative papers have been published from the primary data, while the other papers are currently under review for publication. Additionally, the research findings have been presented in five national and international conferences.