Aims: The dietary intake and reported eating behaviours of adolescents in the UK are a public health concern. Schools are identified as an ideal ‘place’ setting to promote health and improve young peoples’ nutrition outcomes. A gap in the understanding of how healthy secondary school food policy can be implemented, sustainable and effective, may hamper progress to improving school food provision and nutrition education in the UK. Research was conducted to understand the factors which influence healthy school food provision and the adolescent’s food choice to inform and develop a practical framework for schools. Methods: This research involves the development of a practical toolkit which synthesises evidence generated from a mixed methods study and a systematic review. This was informed by an exploration of the secondary school food environment as a potentially ‘obesogenic’ setting, the effectiveness of school food interventions and policy in Europe and UK, included young people’s (11–18 years of age) eating behaviours and priorities in food choice. A pragmatic approach was taken in the integration of evidence, using ecological and behaviour change theory, and joint display principles. Result: A six-phase practical toolkit is presented, guided by ‘What Good Looks Like’ and ‘Whole Systems Approach to Obesity’ principles which can be used to translate the evidence from this research into good school food practice. Conclusion: Improving secondary school food provision across the school day and having a coherent whole school food approach to healthy eating have the potential to significantly improve a young person’s food choice, therefore impacting the nutrient intake of adolescents in the UK. This toolkit helps working towards operationalising this idea.