Background: Neuropsychiatric systemic lupus erythematosus (NPSLE) is a severe SLE complication with limited therapeutic options. While plasma exchange is used, it carries cardiovascular risks and logistical barriers. Case report: We report a 42-year-old East Asian female with SLE who developed progressive edema, dyspnea, and seizures. Imaging and labs revealed cardiorenal dysfunction and neuroinflammatory signs. Peritoneal dialysis (PD) was initiated alongside immunosuppressive therapy (methylprednisolone, telitacicept, cyclophosphamide), leading to resolution of neuropsychiatric symptoms and improvement in renal and hematologic parameters. Proteomic findings: LC-MS/MS analysis of dialysate identified 518 proteins, with functional enrichment pointing to complement activation pathways. By day 4, levels of FCER2 (CD23) and C-reactive protein (CRP), both of which are associated with inflammation, were significantly downregulated, suggesting that PD may facilitate the removal of proinflammatory mediators. Conclusion: PD may serve as a dual-purpose therapy in NPSLE, offering renal support and modulating complement overactivation.