Background: Metabolic syndrome (MetS) is primarily attributed to an unhealthy lifestyle, which is a modifiable risk factor. Researchers have been exploring various strategies, including lifestylemodification programs (LMPs), to prevent the progression of MetS. However, the effectiveness of LMPs on metabolic risks and patient-reported outcomes (PROs) among adults with MetS remains inconclusive. Aim: To evaluate the effectiveness of LMPs on the metabolic risks and PROs among adults with MetS. Methods: A systematic review of randomized controlled trials published from January 1985 to June 2014 was conducted. The review extracted LMP interventions that included outcomes on the metabolic risks and PROs (quality of life and any other psychological health indicators). The quality of the included studies was assessed using the Cochrane Collaboration criteria. Results: Among the five trials included, the most commonly applied intervention components were diet plans, supervised exercise, health education, individual counseling, behavioral modification, and motivational interviewing. Three fifths of the studies were nurse-led, and only one of the selected trials was theory-guided. LMPs can effectively reduce triglyceride levels, waist circumference, and systolic blood pressure. However, few trials consistently confirmed the benefits of metabolic risks, and none revealed a significant effect on high-density lipoprotein, fasting blood glucose, or any PRO, except quality of life. The duration of LMPs in the included trials ranged from 4 to 24 weeks, and durations of at least 12 weeks significantly improved quality of life. Linking Evidence to Action: LMPs had positive effects on some metabolic risks and on quality of life, whereas longer-duration LMPs may have highly beneficial effects on quality of life. The essential elements of LMPs need to be evaluated more thoroughly to determine their effectiveness. Larger and more rigorous randomized controlled trials are required to assess the effectiveness of LMPs on metabolic risks and PROs among adults with MetS.