Abstract Introduction <p>Wilm’s tumor (WT), or nephroblastoma, is the most common primary renal malignancy in children but remains extremely rare in adults, with approximately 300 cases reported in the literature. Due to the limited data, definitive guidelines for adult WT are absent. </p> Case Presentation <p>This case report details an adult WT diagnosed in a 40-year-old female with metachronous liver metastasis and a 10-year follow-up. The patient was incidentally found to have a right renal mass in 2015, which was subsequently diagnosed as adult WT after undergoing a radical nephrectomy. Histopathological analysis revealed a triphasic tumor with a predominantly blastemal component and positive immunohistochemical staining for WT1, CD99, and NSE, confirming the diagnosis. The patient received adjuvant chemoradiotherapy (24 cycles of vincristine, doxorubicin, and actinomycin D and 18 Gray radiation to the flank). Five years later, routine follow-up imaging identified a metastatic lesion in the liver, which was confirmed as metastatic adult WT following a right hepatectomy. Currently, 10 years after the initial diagnosis, the patient remains well with no evidence of recurrence. </p> Conclusions <p>Wilm’s tumor, predominantly a pediatric disease, can occur in adults too. Management involves a multimodal approach, including surgery, chemotherapy, and radiation therapy, with recent advances suggesting the potential for new therapeutic agents. Long-term follow-up is needed, as the disease can present with either synchronous metastasis or, as seen in this case, with distant metachronous metastasis.</p>