While global progress towards several key Sustainable Development Goals is promising, advancements on health, well-being, and – particularly – climate and sustainable consumption remain disappointing. To change this, the primary focus on individual-level behaviours is insufficient: we need to transform behaviours of system actors, including policy makers, healthcare organisations, and multinational corporations. Drawing on my academic research, public health policy experience, and work at an NGO striving for climate justice – I will discuss ways for enhancing the quality, applicability and impact of behavioural science on health and sustainability.