The occurrence of acute myeloid leukemia (AML) with a simultaneous diagnosis of breast cancer (BC) is rarely reported in the literature. The present study reports the case of a 50-year-old female patient diagnosed with AML coexisting with metastatic BC. Following one cycle of treatment with azacytidine in combination with oral venetoclax for AML, the patient achieved complete remission with incomplete hematological recovery. In addition, the mass in the left breast was smaller following adjuvant chemotherapy. However, due to a refusal from the patient to accept an allogeneic hematopoietic stem cell transplantation (allo-HSCT), the patient succumbed 3 months after diagnosis due to septic shock from neutropenia following the third cycle of chemotherapy. Altogether, the present case report highlighted the application of venetoclax, an oral selective B-cell lymphoma-2 inhibitor, both in hematologic malignancies and solid neoplasms, as an effective therapeutic regimen. Considering the fatality rate associated with AML, allo-HSCT is the only available strategy that can be used to achieve the long-term survival of patients with AML and BC.