An 18-year-old, intact male cockatiel (Nymphicus hollandicus) presented with a clinical history of dyspnea, lethargy, and reluctance to perch. Coelomic ultrasonographic examination revealed hypoechoic nodules in the proximity of, and within, the liver. The bird did not respond to supportive care and was euthanatized. At necropsy, the testes were bilaterally enlarged, whitish-tan, firm, and multilobulated. The right hepatic lobe contained a mass that had a similar color and consistency to those in the testes. On histologic and ultrastructural examinations, the diagnosis was bilateral testicular seminoma with hepatic metastasis. To our knowledge, this is the first case of a metastatic bilateral testicular seminoma reported in a cockatiel.