Previous studies have shown that thymoquinone (TQ) exerts protective effects in some models of pesticide-induced immunotoxicity. However, no data exist regarding its possible modulatory effect during imidacloprid (IC)-induced toxicity. Therefore, the aim of this study was to investigate the impact of TQ on IC-induced immunotoxicity. Sixty adult male albino rats were divided into three groups of twenty animals each. The control group was given distilled water orally, while the IC-treated group was orally administered 0.01 LD₅₀ (0.21 mg/kg body weight) of IC insecticide daily for 28 days. The animals in the third group (IC/TQ group) received the same IC dose as the IC-treated group for 28 days in addition to an intraperitoneal (I.P.) injection of TQ (1 mg/kg) once every 7 days. We found that IC induced significant increases (P < 0.05) in total leukocyte counts, total immunoglobulins (Igs) (especially IgGs), the hemagglutination of antibodies, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) and malondialdehyde (MDA) compared to the control group. In contrast, significant decreases (P < 0.05) in phagocytic activity, chemokine expression and chemotaxis were observed in the IC-treated group, as were severe histopathological lesions in the liver, spleen and thymus. Notably, TQ supplementation ameliorated the biochemical, histopathological, and immunological changes induced by IC by increasing phagocytic activity, chemokinesis, chemotaxis, immunoglobulin levels, and the hemagglutination of antibodies, as well as by decreasing hepatic enzymes and serum MDA levels. Taken together, our data reveal the benefits of TQ supplementation for ameliorating IC toxicity by decreasing oxidative stress and enhancing immune efficiency.