Background <p>The role of glucagon-like peptide-1 receptor agonists (GLP1-RAs) in patients with weight regain after bariatric surgery remains unclear. The objective of this study was to determine the efficacy and safety of 12 months of GLP1-RA treatment in a real-world patient population with weight regain after bariatric surgery.</p> Methods <p>A single-centre retrospective observational study. Patients with post-bariatric weight regain subsequently treated with GLP1-RA were identified, and the effect on weight after 12 months of treatment was determined. Data are presented as medians (interquartile ranges) or frequencies (%), and Wilcoxon signed-rank tests and Mann-Whitney U tests were used for paired and nonpaired group comparisons, respectively.</p> Results <p>Forty patients (80% female) were included in the analysis. Liraglutide (3.0&#xa0;mg, daily subcutaneous injection, <i>n</i> = 22) or semaglutide (1.0&#xa0;mg, weekly subcutaneous injection, <i>n</i> = 18) was started 74.5 (51.0, 108.3) months after surgery following a weight regain of 14.7 (10.3, 19.6)%. After 12 months of GLP1-RA treatment, a total body weight, BMI, and percentage excess body weight reduction of 10.5 (6.1, 14.7) kg, 3.7 (2.5, 5.3) kg/m², and 41.7 (22.1, 70.5)% were observed, corresponding to a loss of 99.3 (61.0, 135.4)% of the weight regained (<i>P</i>-value &lt; 0.0001). The observed reduction in BMI was significantly lower with liraglutide than with semaglutide, 3.1 (2.0, 4.7) vs. 4.7 (3.7, 6.0) kg/m² (<i>P</i>-value = 0.04). Adverse events were reported in 13 (32.5%) patients, all of which were mild and transient.</p> Conclusion <p>GLP1-RA therapy with liraglutide or semaglutide for 12 months is efficacious and safe for the treatment of weight regain following bariatric surgery.</p> Clinical trial number <p>Not applicable.</p>