Objective: This study aimed to 1) investigate the psychometric properties of the Climate Change Anxiety Scale or CCAS (Clayton & Karazsia, 2020) and 2) examine the mediating role of climate change anxiety on the link between experience of climate change and behavioural engagement in climate mitigation in Filipino youth. Method: A total of 452 Filipino adolescents responded to the survey (Mean Age = 19.18, SD = 0.99). Results: A modified two-factor model of the CCAS displayed superior fit relative to the other three models tested. Confirmatory factor analysis in Phase 1 yielded a stable two-factor structure with strong factor loadings and good internal consistency. In Phase 2, cognitive-emotional, but not the functional impairment component of climate anxiety, showed a mediating effect on the relationship between experience of climate change and behavioural engagement in climate mitigation. Conclusions: This study is the first to demonstrate that CCAS subscales have distinct mediating roles in linking Filipino adolescents' experience of climate change and mitigation behaviours. Further validation of the CCAS is recommended, as well as further research on the factors that can promote environment-friendly behaviours in Filipino youth.