The study aimed to evaluate the ameliorative potential of Nigella sativa oil (N.s) against the adverse effects induced by atrazine (ATZ) in mice. Four groups were divided into: Control group (untreated); N.s group (N. sativa oil, 2 mL/kg/BW); ATZ group (atrazine 200 mg/kg/BW); ATZ+N.s group (atrazine 200 mL/kg/BW; and N. sativa oil, 2 mL/kg/BW). All doses were administered by gavage once daily for 4 weeks. The atrazine-administered group showed a significant increase in total leukocytes, granulocytes, and agranulocytes and a decrease in red blood cells, hemoglobin, mean corpuscular volume, and packed cell volume. Serum concentrations of aspartate aminotransferase, alanine transaminase, and alkaline phosphatase were high in the ATZ group. Atrazine exposure reduced serum albumin and total protein levels in the blood. A significantly higher concentration of bilirubin, urea, and creatinine was also found in the ATZ group. The simultaneous administration of atrazine and N. sativa led to improvements in all the parameters studied above. Thus, this study revealed that atrazine exposure has toxic effects on hematological parameters, liver, and kidney function, and that N. sativa oil reduces these toxic effects of atrazine in male mice.