This review aimed to summarize modifiable environmental and lifestyle risk factors for childhood myopia and evaluate evidence-based preventive strategies for family, school, and public health practice. Following the PRISMA-ScR framework, relevant studies on children aged 5–18y published up to January 2026 were retrieved from mainstream databases, and eligible literature was synthesized according to study design and evidence level. Reduced outdoor activity, excessive near-work and screen exposure, urban residence, insufficient sleep, and gene-environment interaction are major risk factors for childhood myopia. Daily outdoor activity of 1–2h or longer confers protective effects via promoting retinal dopamine release and inhibiting axial elongation, whereas prolonged close work and excessive screen time notably elevate myopia risk. Optimizing outdoor time, regulating ocular use habits, ensuring sufficient sleep, and implementing school-based interventions are core evidence-based preventive measures, and wearable devices and objective biomarkers can facilitate behavioral management and intervention evaluation. In conclusion, childhood myopia is influenced by multiple adjustable factors; increased outdoor exposure is the most effective preventive measure, and combined behavioral and policy interventions are essential to curb the global prevalence of childhood myopia and prevent subsequent severe visual complications.