Rising sea levels and extreme weather events profoundly affect mental and behavioral health in climate-vulnerable regions. This cross-sectional study surveyed 850 youth aged 16–24 across three coastal districts of Bangladesh. Nearly 70% reported moderate-to-severe climate anxiety, and 45% had engaged in adaptive behaviors such as emergency preparedness and environmental advocacy. Regression analysis showed that perceived community support significantly mitigated anxiety levels (β = -0.32, p < 0.01). The findings emphasize the dual need for mental health interventions and community resilience-building to foster psychological adaptation to climate change among young populations.