Widespread behavior change is essential for mitigating climate change. This study explores how country and income differences are associated with the perceived likelihood of changing climate-relevant behaviors (referred to as perceived behavioral plasticity) and support for climate policies. Using an online survey (n = 4,003) from Denmark, India, Nigeria, and the United States – with 50 % of participants from the top 10 % income bracket – we reveal marked heterogeneity in the perceived plasticity of climate-friendly investment behaviors (e.g., purchasing an electric vehicle) and curtailment behaviors (e.g., reducing red meat consumption). Perceived behavioral plasticity was generally higher in India and Nigeria, though these differences should be interpreted cautiously, as response tendencies might have influenced perceptions and reporting of plasticity. While high-income participants reported greater perceived plasticity of certain investment behaviors and eating less red meat, the relationship between income and perceived plasticity differed substantially across behaviors and countries. We also found that higher perceived behavioral plasticity was related to greater support for domain-matched climate policies, and this relationship was stronger among high-income participants. Taken together, the results reveal substantial income- and country-level differences in perceived behavioral plasticity and show that individuals who perceive greater potential for change also express stronger support for corresponding climate policies. These findings underscore the interdependence between individual behavior and policy support and highlight both socioeconomic and psychological levers for designing more targeted and publicly supported climate initiatives.