BACKGROUND AND OBJECTIVES: Current evidence is lacking on physical activity and nutrition-based interventions focusing on the management of type 1 diabetes mellitus (T1DM) and health-related quality of life among children. To assess the effects of physical activity interventions and nutrition-based interventions for children with T1DM. METHODS: Data sources include the Cochrane Central Register of Controlled Trials, Medline, clinicaltrials.gov, the World Health Organization International Clinical Trials Registry Platform, CINAHL through January 2022. Study selection includes randomized controlled trials of children aged 18 years and below with T1DM comparing either a physical activity intervention, a nutrition-based intervention, or hybrid physical activity and nutrition-based intervention with placebo or no-treatment control. Data were pooled using a random-effects model. Primary outcomes were hemoglobin A1c (HbA1c), and health-related quality of life. RESULTS: Eighteen trials were included. Physical activity compared with the no-treatment group showed a lack of effect on HbA1c (mean difference = -0.58, 95% confidence interval -1.20 to 0.05; P value = .07). Nutrition-based intervention compared with no-treatment control for HbA1c level revealed a lack of effect (mean difference = -0.61, 95% confidence interval -1.48 to 0.26; P value = .17). Limitations include paucity of studies and low quality of evidence caused by the risk of bias. CONCLUSIONS: Despite the lack of significant evidence, the generally favorable results highlight the potential of such interventions in enhancing glycemic control and health-related quality of life. Additionally, promising results from a single physical activity-nutrition-based hybrid intervention in terms of glycemic control indicate the plausible effectiveness of a mixed intervention.