Abstract: Objective: The present study aimed to investigate the effects of useful bacteria isolated from sweet and sour yogurt on the overall performance of antibiotic-free commercial broiler production. Materials and Methods: A total of 128 mixed-sex broiler chicks were randomly divided into 4 groups with 4 replicates where T1, T2 and T3 was treated with a bacterial solution (5 mL L–1) isolated from sweet yogurt, sour yogurt and their combination, respectively and T4 was considered as the control. The experiment was conducted for 34 days and the supplements were added to the drinking water. The data were statistically analyzed using a Completely Randomized Design (CRD). Results: A non-significant effect of yogurt supplementation on feed intake was observed in this study. Yogurt supplementation significantly increased (p<0.05) body weight gain. A highly significant (p<0.01) improvement in body weight gain was recorded for T2. The yogurt supplementation significantly (p<0.01) improved the FCR. The dressing weight was significantly (p<0.05) increased by the supplementation. The difference in survivability among the treatments was non-significant. Further, the highest profit was obtained from T2 (27.17 Tk kg–1), followed by T3 (22.31 Tk kg–1) and T1 (21.00 Tk kg–1). In contrast, the lowest profit was recorded for the T4 (17.08 Tk kg–1). Conclusion: The present study showed promising effects of yogurt supplementation on commercial broiler production without antibiotics, especially sour yogurt, which significantly improved the production performance and net profit. Therefore, it is suggested that sour yogurt could be a safe alternative to antibiotics for commercial broiler production.