This review evaluates the indications and outcomes of one-anastomosis/mini gastric bypass (OAGB/MGB) reversal to normal anatomy. A systematic literature search and meta-analysis was performed in PubMed, Web of Science, and Scopus for articles published by October 1, 2020, including the keywords "one anastomosis gastric bypass," "OAGB," "mini gastric bypass," "MGB," "reversal," "reverse," "malnutrition," and "reversal bariatric surgery". After examining 182 papers involving 11,578 patients, 14 studies were included. A reversal was performed in 119 patients on average 23.6 months after the primary OAGB/MGB surgery. The mean body mass index (BMI) was 22.92 ± 3.47 kg/m and the mean albumin level was 25.17 ± 4.21 g/L at reversal. The mean length of the common channel (CC) was 383.57 ± 159.35 cm, with a mean biliopancreatic limb (BPL) length of 214.21 ± 48.45 cm. Pooled estimation of the meta-analysis of prevalence studies reported a prevalence of 1% for reversal. The major signs and symptoms of protein-energy malnutrition were the leading causes of the reversal of OAGB/MGB. Bleeding, leakage, and death due to severe liver failure were the most reported complications after reversal, with an overall incidence of 10.9%. In conclusion, OAGB/MGB reversal has a prevalence of 1% and has a complication rate of 10.9%. Protein-energy malnutrition with hypoalbuminemia was the most common etiology. The mean lengths of BPL and CC were reported as 215 cm and 380 cm, respectively, in the cases. Therefore, special attention should be paid to malnutrition in all OAGB/MGB patients during follow-up to prevent severe malnutrition and subsequent increase in reversal procedures.