Lupus nephritis is a serious complication of systemic lupus erythematosus, with approximately 20–30% of patients with this diagnosis progressing to end-stage renal disease (ESRD) within ten years. The study examined eight patients with ESRD-LN treated with belimumab during a mean follow-up of 25 months. Belimumab significantly reduced extrarenal disease activity—the SLEDAI score decreased from 6.13 to 1.50 and C3 complement levels improved from 0.64 g/L to 0.8 g/L. Glucocorticoid doses were significantly reduced from 21.25 mg/day to 3.91 mg/day, with three patients completely discontinuing glucocorticoid therapy. Only mild infections were observed during treatment, with no serious infections reported. The results suggest that belimumab is a promising therapeutic option for patients with ESRD-LN that effectively controls disease activity and reduces the need for corticoids, although further studies are needed to confirm long-term efficacy and safety.