Ampullary adenocarcinoma (AD) with testicular metastasis is exceptionally rare. This case report presents the clinicopathological features of a rare case of ampullary AD with testicular metastasis, confirmed by clinical history, histomorphology, and immunohistochemistry. A 63-year-old male underwent pancreaticoduodenectomy in April 2023 for obstructive jaundice and imaging findings of a bile duct space-occupying lesion. Postoperative pathology revealed moderately to poorly differentiated ampullary AD (pancreatobiliary type) with observed intravascular tumor thrombi, perineural invasion and lymph node metastasis. Fifteen months after surgery, the patient was readmitted upon presenting with a progressively enlarging right testicular mass, accompanied by discomfort and a dragging sensation. Imaging suggested metastatic potential, and radical resection of the right testis was performed. Histopathological examination of the postoperative specimen revealed multifocal AD nests infiltrating the testicular tissue. The AD components were positive for CK, CK7, CK19, CK20, and villin and negative for PLAP, inhibin-α, vimentin, MelanA, alpha-fetoprotein, glypican-3, and SALL4. In conclusion, patients with ampullary AD with testicular metastasis often present with scrotal swelling and pain. Diagnostic clues may be derived from patient age, clinical course, and imaging findings, while definitive diagnosis relies on histopathology and immunohistochemistry.