Objective: To identify the behaviour change techniques and intervention components associated with the promotion of physical activity (PA) for children and young people living with and beyond cancer. Design and main outcome measures: A systematic review and narrative synthesis was conducted on the evidence on PA interventions for children and young people (up to 30 years of age) living with and beyond cancer using a social ecological framework. Results: Out of 12 studies, 8 were shown to change PA. Intervention components included: 1) behavioural (Instruction on how to perform the behaviour, credible source, behavioural demonstration and rehearsal), 2) cognitive-emotional (targeting attitude, perceived behavioural control, intentions, resilience and achievement) 3) socio-cultural (family and peer support for PA), 4) environmental (providing access to resources, environmental restructuring, safety), 5) demographic (child, adolescent, young adult or mixed) and 6) medical (tailored exercise depending on age and cancer stage). Conclusions: Interventions designed to increase physical activity participation and adherence during and beyond cancer treatment for young people should integrate psychosocial (behavioural, cognitive-emotional, social), environmental and medical intervention components. Our conceptual model can be used to inform the development of interventions and guides future research objectives and priorities.