ObjectiveTo systematically review, evaluate and summarise the best evidence regarding exercise program for women at high risk of gestational diabetes mellitus (GDM) from domestic and international databases, and to provide recommendations for them to prevent GDM.MethodsWith the "6S" evidence model, the two clinical decision support systems of UpToDate and BMJ Best Practice, as well as several international guideline websites, were employed. The search encompassed both Chinese and English databases, including PubMed, Embase, Cochrane Library and CNKI. In addition, six relevant associations were reviewed for the best evidence on exercise in high-risk GDM populations. Evidences were graded using the Australian JBI Evidence Pre-Grading and Evidence Recommendation Levels System, with the strength of recommendations based on the JBI FAME structure and grading principles.ResultsA total of 39 articles were included, comprising 16 guidelines, 17 systematic reviews, 3 expert consensus documents and 3 evidence summaries. Among these, 21 articles (53.8%)were of high quality, and 18 articles (46.2%) moderate. 54 best evidence recommendations were summarized across four domains: medical screening for high-risk GDM populations, exercise risks, exercise prescriptions, and other suggestions/precautions. Of these, 37 recommendations (68.5%) were assigned a recommendation level of 1, one recommendation (1.8%) a level of 2, nine recommendations (16.7%) a level of 4, and seven recommendations(13.0%) a level of 5. Additionally, 50 recommendations (92.6%) were strongly endorsed, while four recommendations (7.4%) were weakly endorsed.ConclusionThe evidence highlights the necessity of pre-exercise assessments for women at high risk of GDM. Regular, moderate-intensity aerobic, resistance, or hybrid exercise during pregnancy−targeting at least 150 minutes per week or 30 minutes per day in at least three sessions per week−was recommended to reduce the risk of GDM and associated pregnancy complications. Additionally, personalized, well-designed, and professionally supervised exercise programs are encouraged to enhance both the safety and adherence.