Additives in fish feeds are used worldwide to provide better productivity and improve fish’s health in facing disease outbreaks. This study aimed to identify the protective effect of taurine on the immune-related parameters and antioxidant enzyme activities of Seriola rivoliana juveniles after being challenged with LPS (lipopolysaccharide). Previously, the fish were submitted to a feeding trial for 60 days with feed enriched with different doses of external taurine (0, 1%, and 2%). Juveniles fed on different doses of taurine were injected with LPS (0%, LPS+T0%; 1%, LPS+T1%; 2%, LPS+T2%), and a control group was injected with saline solution (LPS-). The immune-related mRNA expression was evaluated, as were lysozyme enzyme activity and antioxidant enzyme activities (superoxide dismutase—SOD; catalase). Regarding immune mRNA expression, all the treatments had a peak of expression at 24 h post-LPS-injection, with a sharp decrease at 72 h post-injection, reaching similar mRNA expression as at 0 h post-injection. The results showed that the LPS+T2% treatment improved the expression of il1-β, tnf-α, and tlr-3 at 24 h post-LPS injection. Antioxidant and lysozyme activities were higher in both treatments with taurine when compared to the LPS+T0% and LPS- groups after 72 h post-LPS injection. These results suggest using 2% of exogenous external taurine can improve immunocompetency and counteract the oxidative stress caused by exposure to LPS in S. rivoliana juveniles.