Knowledge mobilisation aims to increase research impact in policy and practice. 'Mobilising' knowledge implies a social interaction and involves an iterative, collaborative process. We argue that this process is strengthened when underpinned by systems thinking. Previous research has integrated systems thinking with knowledge mobilisation. We built on this to develop an applied tool to support prevention researchers seeking to incorporate systems thinking into their knowledge mobilisation work. We refer to this tool as the 'systems thinking guide for knowledge mobilisation'. Our guide was developed through a stepwise process that included: 1) An inductive thematic synthesis of previous research in this area; 2) Reflexive deliberation to identify critical focus areas, drawing on the synthesis and the authors' experiences of applying systems approaches to knowledge mobilisation; 3) Development of a set of questions designed for end users to consider against the backdrop of their own research and contexts; 4) Trialling these questions through a series of workshops; and 5) Revision based on user feedback. The proposed systems thinking guide includes 13 questions and 18 subquestions to help researchers frame their knowledge mobilisation strategies using a systems perspective. Our next steps are applying this guide to other research projects and reviewing and reporting on its implementation and real-world use. In the meantime, we invite other research teams to test this tool and contribute constructive feedback on its usefulness and potential further development.