We present the case of an 83-year-old woman who presented with acute bioprosthetic valve thrombosis following surgical aortic valve replacement. On postoperative day 7, transthoracic echocardiography revealed reduced leaflet mobility in an implanted bioprosthetic valve, and contrast-enhanced computed tomography showed hypoattenuated leaflet thickening, leading to the diagnosis of prosthetic valve thrombosis. This case demonstrates that bioprosthetic valve thrombosis can occur even in the acute phase following surgical aortic valve replacement, highlighting the importance of early diagnosis and intervention. Close monitoring of leaflet mobility and thickening via transthoracic echocardiography is essential, with contrast-enhanced computed tomography serving as a valuable complementary tool.