Background and Aims: Obesity is a growing public health concern and major risk factor for conditions including non‐alcoholic fatty liver disease (NAFLD), cardiovascular disease, and diabetes. This study aimed to assess the early effects of one anastomosis gastric bypass (OAGB) surgery on metabolic risk factors and liver‐related parameters in patients with morbid obesity. Methods: This prospective longitudinal study included 41 patients aged over 30 years who had a medical indication for bariatric surgery. All participants underwent one anastomosis gastric bypass (OAGB) surgery and were assessed preoperatively and 4 months postoperatively for anthropometric and biochemical parameters, liver ultrasonographic and elastographic findings, as well as visceral and subcutaneous fat distribution. Results: Four months postoperatively, mean body weight and BMI decreased significantly to 90.2 ± 18.1 kg ( p < 0.001) and 32.6 ± 5.5 kg/m ² (95% CI: 9.5 [8.5–10.6], p < 0.001), respectively. Glycemic indices, lipid profiles, and liver enzymes improved significantly, alongside reductions in visceral and abdominal subcutaneous fat thickness ( p < 0.001). Shear wave elastography (SWE) measurements also significantly decreased (95% CI: 0.9 [0.6–1.1], p < 0.001). By follow‐up, 70.7% of patients showed no ultrasonographic evidence of hepatic steatosis, reflecting a 65.8% increase in resolution compared to pre‐surgical status, with 11 classified as grade 1, one as grade 2, and none as grade 3. Conclusion: OAGB surgery is associated with significant early improvements in obesity, NAFLD and its related metabolic risk factors in morbidly obese patients. Future studies should assess long‐term outcomes to determine the sustainability of these early benefits.