Purpose: This study aimed to evaluate the effectiveness of physical activity (PA) interrupting prolonged sitting (PS) on postprandial glycemia and insulin responses among adults. Methods: PubMed, EMBASE, Cochrane Library, Web of Science, CINAHL, PsycINFO, and the China National Knowledge Infrastructure databases were searched through September 30, 2020. Randomized controlled trials (RCTs) that examined the effect of all forms of PA interrupting PS on postprandial glycemia and/or insulin responses among adults without chronic diseases were included in this study. The risk of bias of included studies was evaluated based on the Cochrane tool. A network meta-analysis was performed to estimate the summary standardized mean differences (SMDs) with 95% confidence intervals (95%CIs) with random effects. Results: Thirty crossover RCTs were included in our review. These RCTs included 9 types of interventions that interrupted PS. When compared to PS by itself, light-intensity PA intermittent interrupting (LPA-INT) PS and moderate-intensity PA intermittent interrupting (MPA-INT) PS significantly lowered postprandial glycemia (SMD = 0.46, 95%CI: 0.70 to 0.21; SMD = 0.69, 95%CI: 1.00 to 0.37, respectively) and significantly reduced postprandial insulin response (SMD = 0.46, 95%CI: 0.66 to 0.26; SMD = 0.47, 95%CI: 0.77 to 0.17, respectively). Results of the clustered ranking plot indicated that MPA-INT was the most effective intervention in lowering postprandial glycemia and insulin responses. Conclusion: Replacing PS with MPA-INT or LPA-INT has a positive effect in reducing postprandial glycemia and insulin responses, with MPA-INT being the optimal intervention strategy.