Abstract Background Weight loss outcomes after bariatric surgery are less favorable in super morbidly obese patients (BMI ≥50 kg/m²). Non-response, either defined as insufficient weight loss or weight regain after initial successful weight loss, is a matter of serious concern in these patients. The primary banded Roux-en-Y gastric bypass has shown promising results regarding weight loss in the bariatric population. However, up to now, long-term comparative data about the banded and non-banded bypass in superobese patients is lacking. The aim of this study is to assess the added value of the banded Roux-en-Y gastric bypass in superobese patients on long-term weight loss outcomes. Methods This single center study will evaluate superobese patients who receive a non-banded Roux-en-Y gastric bypass (NB-RYGB) and a banded Roux-en-Y gastric bypass (B-RYGB). Data from the NB-RYGB group will be collected in retrospect, while data from the B-RYGB group will be collected prospectively. When performing a B-RYGB, a 7.0–8.0 cm silastic ring (MiniMizer®) will be placed proximal to the gastrojejunostomy. The main outcomes of this study are weight loss and non-response during a 10 year follow-up period. Secondary outcomes are reduction of obesity related comorbidities and medication, (ring-related) morbidity and mortality, complications, re-operations, patient satisfaction and health-related quality of life. A total of 142 patients will be included in this study. Discussion This study will help establish the clinical utility of the B-RYGB in superobese patients. Trial register NL8093. Registered 15 October 2019 - Retrospectively registered on the Dutch Registry of Clinical trials, www.trialregister.nl