BACKGROUND Physical activity promotes health and learning. However, up to 80% of the children in industrialized countries do not achieve the recommended level of daily physical activity. By encouraging children to use active school transportation (AST), it is possible to increase their overall physical activity. OBJECTIVE The aim of this paper was to present the development of an AST intervention using Intervention Mapping (IM) to promote children’s physical activity. METHODS The principles of IM were applied to guide the development of the intervention. The process was divided into 3 phases. First, a literature review and collection of experiences of stakeholders were carried out to gain a broad perspective on the problem and possible solutions. Thereafter, an analysis of the critical environmental and behavioral factors affecting outcome was conducted, which guided the choice of tangible components of the intervention. Finally, a plan of evaluation and implementation was established. RESULTS A structured program to increase AST among children was developed, consisting of 3 subsequent phases that are described in detail. Implementation took place, and evaluation of the intervention is being carried out. CONCLUSIONS IM proved to be a valuable method to develop a structured AST intervention for children. By following the steps of the IM process, it became evident that empowerment and gamification are 2 promising avenues to consider when designing AST interventions in a school context. By engaging end users and including important agents, such as parents and teachers, who control the environmental factors, the possibility to design a sustainable program increases. In addition, gamification made it possible to integrate learning into AST, which could motivate schools to devote time and effort to implementing this program.