The climate crisis is adversely impacting mental health and wellbeing. Research on interventions to address these impacts remains scarce, particularly in humanitarian settings. This study used a modified Delphi process to identify research priorities for mental health and psychosocial support (MHPSS) and climate crisis research, drawing on the perspectives of those with demonstrated interest, engagement, and/or expertise in MHPSS and the climate crisis. The study consisted of two online surveys. In the first survey, demographic and qualitative data were collected and analysed to generate a list of research priorities and a concept map to describe the area of climate crisis and MHPSS research. In the second survey, participants ranked and rated their agreement with priorities and provided recommendations for modification of individual priorities and the concept map. In total, 91 experts working primarily but not exclusively in MHPSS programming or practice participated in the study. Consensus was reached on 20 research priorities, and 8 top-ranked priorities were identified. Given the urgency of the climate crisis, MHPSS and climate crisis research must contribute to mitigating and adapting to the climate crisis while promoting both mental health and psychosocial wellbeing and just international development.