Contemporary climate change advocacy, science, and policymaking widely incorporate justice framing, but little is known about public understanding of climate justice and the degree to which justice-related beliefs function as a motivation for climate action and policy support. We assessed climate justice awareness among adults in 11 countries spanning the Global North and South (N = 5,627). Most participants (66.2%) had never heard of climate justice. Endorsement of common climate justice-related beliefs was widespread (e.g., acknowledging the need to give voice to frontline communities, and the underpinning role of colonialism and capitalism in the climate crisis). Climate justice beliefs were associated with various indices of climate action and policy support. These associations tended to be stronger in high emitting countries and where social inequality is a more politically salient topic. The results highlight a risk that less privileged groups, often the most affected, are left out of climate justice discourse.