As the climate crisis demands global engagement, it is crucial to understand how interventions influence individuals across cultural backgrounds. Are interventions more effective when aligned with the cultural values of a target population? To investigate, we evaluated eleven behavioral interventions aimed at stimulating climate change mitigation, along cultural individualism and collectivism orientations, in a large sample (N=59,440) spanning 63 countries. At baseline, we found the more individualistic a nation, the less its residents believed in climate change, supported mitigation policy, and intended to share information, but did not plant fewer trees in an online task. Critically, while some interventions were more effective in individualistic (decreasing psychological distance), and some in collectivistic nations (emphasizing social norms), others were effective in both (writing a letter to the future generation). These results reveal that individualism is a significant barrier to climate mitigation, and the efficacy of interventions hinges on cultural contexts.