Introduction: One anastomosis gastric bypass (OAGB) prevalence is increasing worldwide and shows good mid- to long-term results. Data on long-term outcomes of revisional OAGB (rOAGB) is limited. This study’s objective was to evaluate the long-term outcomes of patients undergoing primary OAGB (pOAGB) and rOAGB. Methods: A retrospective analysis of a prospectively maintained patient registry at a single-tertiary center. Patients undergoing OAGB from January 2015 to May 2016 were included and grouped into pOAGB and rOAGB. Results: There were 424 patients, of which 363 underwent pOAGB, and 61 underwent rOAGB. Baseline characteristics were insignificantly different between groups except for the type 2 diabetes (T2D) rate which was higher in pOAGB (26% vs. 11.5%, p = 0.01). The mean follow-up time was 98.5 ± 3.9 months, and long-term follow-up data were available for 52.5% of patients. The mean total weight loss (TWL) was higher in the pOAGB group (31.3 ± 14 vs. 24.1 ± 17.6, p = 0.006); however, TWL was comparable when relating to the weight at primary surgery for rOAGB. The rate of T2D and hypertension resolution was 79% and 72.7% with no difference between groups. Thirteen patients (5.9%) underwent OAGB revision during follow-up, with no difference between groups. Two deaths occurred during follow-up, both non-related to OAGB. Conclusion: OAGB is effective as a primary and as a revisional procedure for severe obesity with good long-term results in terms of weight loss and resolution of associated diseases. In addition, the revisional surgery rates and chronic complications are acceptable. Further large prospective studies are required to clarify these data.