Although sleeve gastrectomy (SG) is the most performed metabolic and bariatric surgery (MBS) worldwide, some patients require conversional procedures due to weight recurrence or late complications. Recently, one-anastomosis gastric bypass (OAGB) gained popularity as a viable option to address those problems. The aim of this meta-analysis is to assess the safety and efficacy of conversional OAGB after primary SG in the management of patients with obesity. Cochrane, Embase, PubMed, Scopus, and Web of Science were searched for articles from their inception to February 2023 by two independent reviewers using the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) system. The review was registered prospectively with PROSPERO (CRD42023403528). From 1,117 studies screened, twenty studies met the eligibility criteria, with a total of 1,057 patients with obesity undergoing conversional OAGB after primary SG. The mean age ranged from 28.2 to 49.5years, and 744 patients (75.2%) were women. At one year after revisional OAGB, the pooled mean percent excess weight loss (%EWL) was 65.2% (95%CI: 56.9, 73.4, I2 = 97%). The pooled mean %EWL after conversional OAGB was 71.1% (95%CI: 62.2, 80.0, I2 = 90%) at two years and 71.6% (95%CI: 61.0, 82.2, I2 = 50%) at five years. Additionally, resolution rates of diabetes and hypertension were 65.4% (95%CI: 0.522, 0.785, I2 = 65%) and 58.9% (95%CI: 0.415, 0.762, I2 = 89%), respectively. Our meta-analysis demonstrated OAGB as an effective conversional procedure after primary SG in terms of weight loss and obesity-associated medical problems for selected patients. Despite the promising results, further randomized controlled studies with larger sample sizes and more extended follow-up periods are necessary to determine if the OAGB is the best conversional surgery after SG.