Background: Public health emergencies require rapid responses from experts. Differing viewpoints are common in science, however, “mixed messaging” of varied perspectives can undermine credibility of experts, reduce trust in guidance, and act as a barrier to changing public health behaviours. Collation of a unified voice for effective knowledge creation and translation can be challenging. This work aimed to create a method for rapid psychologically-informed expert guidance during the COVID-19 response. Method: TRICE (Template for Rapid Iterative Consensus of Experts) brings structure, peer-review, and consensus to the rapid generation of expert advice. It was developed and trailed with 17 core members of the British Psychological Society COVID-19 Behavioural Science and Disease Prevention Taskforce. Results: Using TRICE, we have produced 15 peer-reviewed COVID-19 guidance documents based on rapid systematic reviews, co-created by experts in behavioural science and public health, taking 4-155 days to produce, with approximately 17 experts and a median of 10 drafts per output. We provide worked-examples and key considerations, including a shared ethos and theoretical/methodological framework, in this case, the Behaviour Change Wheel and COM-B. Conclusion: TRICE extends existing consensus methodologies and has supported public health collaboration, co-creation of guidance and translation of behavioural science through explicit processes in generating expert advice for public health emergencies.