An 85-year-old woman underwent emergent splenectomy due to left abdominal pain and active bleeding in a massively enlarged spleen. The histological diagnosis was splenic marginal zone lymphoma (SMZL). A prolonged activated partial thromboplastin time (APTT) was noted, and additional tests led to the diagnosis of type 2A-like acquired von Willebrand syndrome (AVWS). An APTT cross mixing test ruled out the presence of inhibitors. She received eight courses of rituximab monotherapy. The coagulation data showed no improvement, possibly because the lymphoma showed a poor response to the treatment. AVWS rarely causes bleeding in solid organs. This is the first case of SMZL with AVWS diagnosed via splenic bleeding.