BACKGROUND: Worry about climate change may be associated with poorer mental health but also with greater political engagement. We determined trajectories of climate change-related worry over adolescence and whether these were associated with depression symptoms and greater engagement with news and politics in late adolescence. METHODS: At ages 10-11, 12-13, 16-17 and 18-19 years, adolescents participating in the Kindergarten cohort of the Longitudinal Study of Australian Children rated their worry about climate change. At age 18-19 years, participants reported on depression symptoms and engagement with news and politics. Latent profile analysis determined trajectories of climate change-related worry across all time points (N=2244). Linear regression analyses examined the association between trajectories and outcomes at 18-19 years. RESULTS: Thirteen per cent (n=290) of adolescents had high persistent worry. The largest proportions had moderate (n=559, 24.9%) or increasing worry (n=546, 24.3%), followed by persistent low worry (n=376, 16.8%), slightly decreasing worry (n=297, 13.2%) and steeply decreasing worry (n=176, 7.8%). Adolescents with high persistent worry had higher depression symptoms at age 18-19 years compared to the moderate group, while those with increasing worry did not. The high persistent and increasing worry groups reported greater engagement with news and politics across several measures. CONCLUSION: This is the first study to track climate-related worry and outcomes in young people across adolescence. A substantial number of Australian adolescents experience high or increasing worry about climate change, which is associated with greater societal engagement.