Due to the numerous pharmacological impacts of Spirulina platensis (SP), the effects of SP on the oxidative status of Nile tilapia farmed under chlorpyrifos (CPF) ambient toxicity were considered in this study. Fish (60 ± 6.1 g) was randomly stocked in five groups where the SP free diet was fed to the control group while the second one was fed 1% SP without CPF exposure. Additionally, CPF (15 μg/L) was added in water and fish were fed with SP at 0, 0.5, and 1% (third, fourth, and fifth groups, respectively). Samples of blood and gills, kidneys, and liver tissues were assayed for biochemical measurements. Fish exposed to CPF exhibited significant (p ≤ 0.05) increments of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), cholesterol, urea, creatinine, and malondialdehyde (MDA), while significantly decreased total protein, albumin, and antioxidative enzyme activities (superoxide dismutase (SOD) and catalase (CAT) were observed in tilapia exposed to CPF (p ≤ 0.05). In contrast, SP feeding resulted in decreased levels of ALT, AST, ALP, cholesterol, urea, and creatinine as well as increased total protein, albumin, SOD, and CAT activities. Based on the obtained results, it can be suggested that SP is efficient in protecting Nile tilapia from CPF toxicity by increasing the antioxidative response.