Chronic pruritus following biliary atresia (BA) surgery significantly impairs quality of life, and conventional treatments, including ursodeoxycholic acid, nalfurafine, and antihistamines, often provide insufficient relief. We report a seven-year-old girl with persistent pruritus despite multiple treatments for both cholestatic pruritus and atopic dermatitis (AD). She exhibited severe itching, sleep disturbances, and irritability, refractory to topical corticosteroids, tacrolimus, Janus kinase inhibitors, and systemic therapies. Laboratory findings revealed mild liver dysfunction and elevated total immunoglobulin E, suggesting an allergic predisposition. Given the lack of response to standard therapies, nemolizumab, an interleukin-31 (IL-31) receptor antagonist, was administered. Within one month, pruritus dramatically improved, with her Eczema Area and Severity Index and Patient-Oriented Eczema Measure scores decreasing from 11.0 and 19 to 1.2 and 0, respectively. Sleep disturbances resolved, allowing discontinuation of multiple medications, and her overall well-being significantly improved. This case highlights the potential role of IL-31 in cholestatic pruritus and suggests that IL-31 blockade with nemolizumab may be an effective therapeutic option for refractory pruritus in pediatric patients with BA, warranting further investigation into its broader clinical applications beyond AD.