This study aimed to investigate the efficacy of probiotic supplementation in mitigating stress and improving performance, carcass yield, carcass quality parameters, sensory acceptability, microbiological quality and economic profitability of broilers reared at different stocking densities. Two hundred and forty chicks were divided into four groups; two groups were reared at a low stocking density (LSD, 10 bird/m2), including one group that was provided with Protexin® probiotic (Enterococcus faecium) supplemented in water (LSDP). Similarly, the other two groups were reared at a high stocking density (HSD, 15 bird/m2), including one group that was provided with the same probiotic supplementation (HSDP). Throughout the growing cycle, bird performance was monitored. At the end of the growing cycle, stress indicators were measured in blood. Besides, carcass and giblet weights, dressing yield, carcass quality parameters, sensory acceptability, microbiological quality and economic profitability were assessed. As a result, HSD mostly impaired broiler performance, increased stress indicators, reduced carcass yields, carcass quality parameters and sensory acceptability, while boosted profitability and slightly lowered microbiological quality. On the other hand, probiotic supplementation reversed the negative effects of HSD. As probiotic supplementation boosted broiler performance, reduced blood stress indicators, increased carcass and giblet yields, carcass quality parameters and sensory scores, besides, it improved the microbiological status of broiler meat in terms of fecal coliforms and E. coli MPN. To conclude, rearing broilers at high stocking density induced stress, compromised performance and reduced carcass quality. These negative impacts could be successfully faced by using probiotic supplementation in drinking water.