Background Non-pharmacological interventions are the first line of Gestational diabetes mellitus (GDM) management. Community-based interventions are cheaper, more accessible, with higher patient satisfaction. Objectives To systematically review community-based non-pharmacological interventions and evaluate their effectiveness for GDM. Search Strategy Twelve bibliographic databases and reference list of related studies from inception until January 2022. Selection Criteria All primary studies of community-based non-pharmacological interventions for GDM reported in English which investigated any behavioural or clinical outcome(s). Data Collection and Analysis Data were extracted using modified Cochrane’s data extraction template. Studies were evaluated using Cochrane Collaboration’s risk of bias tool. Narrative synthesis was used to summarise findings. This study is registered with PROSPERO (CRD42021257634). Main Results 27 studies involving 6,242 pregnant women with GDM involved self-management programmes, medical nutrition/diet therapy, exercise/physical activity, combined diet and exercise, calcium plus vitamin D supplementation, and continuous glucose monitoring. Self-management programmes were more effective than routine care in improving self-efficacy, two-hour postprandial blood glucose, and lifestyle behaviours but were as effective as routine care in improving infant birth weight. Self-management programmes were superior to or as effective as usual care in improving fasting blood glucose, blood glucose control, glycated haemoglobin, macrosomia, and preterm delivery. Medical nutrition/diet therapy was more effective than usual care in improving postprandial blood glucose levels. Limited/conflicting evidence was found for other outcomes and interventions. Conclusions Community-based non-pharmacological interventions are more effective than placebo; and are more/as effective as usual care. Self-management programmes and medical nutrition/diet therapy had the most promising GDM outcomes.