This systematic review aimed to investigate the effect of school-based physical activity interventions on physical fitness and psychological responses in children and young people. Studies were conducted from Web of Science, Scopus and PubMed databases between 1 January 2017 and 1 December 2022 according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist. For the research to be conducted in the databases, "School-Based Intervention", "physical fitness ", "Psychology", School-based intervention, physical fitness and psychological responses were used in the title and abstract. The database review revealed seventy-four (74) studies. However, after eliminating seventeen (17) duplicate studies, fifty-five (57) studies remained. Subsequently, seventeen (17) studies were eliminated after reviewing the abstracts. After forty (40) studies were thoroughly analysed, eighteen (18) publications not involving psychological factors, five (5) publications involving research methods and six (6) review studies were excluded. The remaining eleven (11) studies were used after review. The results of the present systematic review showed that school-based physical activity interventions contribute positively to children's physical fitness and psychological health while ensuring a healthy life for years to come.