Background: Ventral hernia repair remains a common surgical procedure with ongoing debate regarding optimal mesh placement. This study aimed to compare the outcomes of onlay versus sublay mesh repair techniques for ventral hernia. Methods: A prospective randomized controlled trial was conducted at a tertiary care center between January 2023 and December 2024. Adult patients with ventral hernia (fascial defect size 3-15 cm) were randomized to either onlay (n=153) or sublay (n=155) mesh repair. Primary outcome was hernia recurrence at 12 months. Secondary outcomes included perioperative parameters, complications, patient-reported outcomes, and cost-effectiveness. Results: Baseline characteristics were comparable between groups. The sublay technique was associated with longer operative time (105.6±22.4 vs. 78.3±18.7 minutes, p<0.001) and greater blood loss (110 vs. 75 mL, p<0.001). However, seroma formation (7.7% vs. 24.2%, p<0.001), surgical site infection (5.8% vs. 13.7%, p=0.018), and hernia recurrence at 12 months (3.9% vs. 11.1%, p=0.017) were significantly lower in the sublay group. Multivariate analysis identified onlay repair as an independent predictor of recurrence (aOR=3.18, 95%CI:1.18-8.57, p=0.022). Patient satisfaction (8.2±1.3 vs. 7.4±1.6, p<0.001) and physical component summary of SF-36 (49.7±7.8 vs. 46.3±8.2, p<0.001) were significantly better in the sublay group. Conclusion: Despite requiring longer operative time and higher resource utilization, sublay mesh repair for ventral hernia demonstrates superior outcomes in terms of reduced seroma formation, surgical site infection, and recurrence rates, along with better patient satisfaction and quality of life. These findings support the preferential use of the sublay technique, particularly in high-risk patients.