Infection-related glomerulonephritis (IRGN) is an immune-mediated glomerular injury triggered by infectious agents. This article reports a case of immune complex-mediated glomerulonephritis following acute hepatitis B virus infection, which continued to progress despite standard antiviral and immunosuppressive therapy. Given the significant elevation of soluble complement membrane attack complex (sC5b-9), an indicator of terminal complement pathway activation, the patient was treated with eculizumab. Following treatment, the patient's urine protein-to-creatinine ratio significantly decreased, hypoalbuminemia and hematuria markedly improved, and sC5b-9 levels declined. This case suggests that abnormal complement system activation may be a key mechanism driving disease persistence in some patients with IRGN. For those unresponsive to conventional therapy, complement function screening and targeted terminal complement pathway inhibition may represent an effective salvage strategy.