Women with a history of gestational diabetes mellitus (GDM) are at a higher risk of developing type 2 diabetes. Several postpartum lifestyle intervention studies have been conducted for this high-risk group; however, the randomized clinical trials have not been evaluated systematically. Thus, the aim of this article is to evaluate the outcomes of clinical trials that focus on diabetes prevention among women with DGM. This systematic review utilized Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Chinese and US databases were searched. Randomized controlled trials of postpartum lifestyle interventions to prevent type 2 diabetes in women with prior GDM were reviewed. Outcomes included in this review are type 2 diabetes incidences, insulin insistence, and weight-related measures. The effect size of these outcomes in each study was computed. Data on intervention components were extracted, including type (in-person vs. technology-based), content (diet or physical activity or both), form (individual session vs. group session), duration, intensity, evaluation time point, and program delivery. A total of 12 studies met the inclusion criteria. The mean annual type 2 diabetes mellitus (T2DM) incidence of the intervention group was lower than that of the comparison group (6.0% vs. 9.3%), although there was no statistical difference between the two groups. About 50% of these studies and two-thirds of studies, respectively, reported a significant decrease in insulin resistance-related measures and weight-related measures in the intervention group compared with the comparison group. The median intervention duration and study length were 6 months. Postpartum lifestyle interventions can be effective in reducing T2DM development and insulin resistance, and decrease weight in women with GDM history, regardless of the intervention types (technology-based or in-person). Effective interventions typically include dietary changes while some physical activity changes can also improve outcomes. However, more interventions with long-term efficacy evaluation are warranted.