Background: Sleeve gastrectomy (SG) is effective but prone to late recurrent weight gain (RWG). Ring-augmented SG (Ra-SG) may preserve restriction and enhance long-term durability. Methods: In this single-center, prospective, single-blind randomized trial, adults with a BMI > 50 kg/m² were randomized to SG or Ra-SG and followed for 36 months. The primary endpoint was percent total weight loss (%TWL) at 36 months. Secondary outcomes included RWG, gastric pouch volumetry, relapse of associated medical problems, complications, endoscopic findings, laboratory parameters, and patient-reported outcomes (SF-36, Suter). Results: Ra-SG produced significantly greater weight loss at 36 months (48.8 ± 8.3 vs. 45.5 ± 9.0%TWL; mean difference 3.25% points, 95% CI 0.86 to 5.63; p 0.008). Exploratory analyses showed lower rates of clinically significant RWG (≥ 30% regain: 5.9% vs. 16.3%; absolute risk difference − 10.4%, 95% CI − 19.6 to − 1.2; p = 0.033) and smaller pouch volumes (160.1 ± 8.9 vs. 194.2 ± 10.3 mL; p < 0.001). Perioperative complications were infrequent and comparable. At three years, the prevalence of endoscopic GERD was similar (17.3% vs. 19.6%). Food tolerance scores were consistently better after SG (all p < 0.05). HRQoL improved significantly in both groups, with no differences observed at 36 months. Two Ra-SG patients (1.8%) underwent ring removal. Conclusions: Ra-SG enhanced weight-loss durability and lowered RWG compared to SG, with similar safety and GERD outcomes but decreased food tolerance at mid-term. Ra-SG may be considered in patients at higher risk of RWG, though multicenter studies with longer follow-up are needed to confirm these findings.