IntroductionChemsex is defined as drug use to enhance sexual pleasure. Global literature illustrated the pervasiveness of chemsex among men who have sex with men (MSM) and transgender women (hijra) for prolonging anal intercourse, reducing pain and intensifying pleasure, oftentimes without condoms. Global literature highlighted the association between chemsex and unsafe sexual behaviours. These circumstances warrant targeted chemsex research to explore the chemsex situation. The study aims to explore the overall dynamics of chemsex among MSM, male sex workers (MSW) andhijrain Dhaka, Bangladesh and formulate culturally relevant, context-specific, gender-sensitive and evidence-based recommendations for chemsex interventions.Methods and analysisThis will be a sequential, exploratory, mixed-methods study. Data will be collected at four drop-in centres in Dhaka in three phases. To explore issues related to chemsex, the formative phase (phase 1) will generate evidence on the overall dynamics of chemsex through a literature review and qualitative interviews. Qualitative data will be manually analysed using thematic analysis. In phase 2, a cross-sectional survey will be conducted among 458 MSM, male sex workers andhijrato measure the prevalence, reasons and sexual risk behaviour associated with chemsex. In phase 3, qualitative interviews will be conducted with the participants involved in chemsex, service providers and relevant stakeholders to add qualitative depth to survey responses. In this phase, service provision will also be investigated for people engaging in chemsex. Moreover, based on the findings of phases 1 and 2, and qualitative interviews of phase 3, a preliminary chemsex intervention model will be developed through a series of intervention design workshops.Ethics and disseminationEthical approval has been attained from the Ethical Review Committee of icddr,b. Informed consent will be obtained from the participants, and confidentiality will be maintained during data collection and storage. Findings will be disseminated via several platforms including dissemination seminars, scientific articles and study report.