Metastasis of breast cancer to the uterus is quite rare. The majority of reported cases have evolved from previously known invasive ductal and lobular carcinomas of the breast. Herein, a rare case of invasive micropapillary carcinoma of the breast that was diagnosed via endometrial biopsy, without a previous diagnosis or history of breast cancer, was presented. A 58-year-old postmenopausal patient, who had no history of cancer, presented with complaints of abnormal uterine bleeding (AUB) that had begun 2 weeks prior. After undergoing transvaginal ultrasonography, endometrial biopsy, tomography, and positron emission tomography/computed tomography, the patient was preliminarily diagnosed with invasive carcinoma of the breast. The biopsy confirmed the diagnosis of metastatic invasive micropapillary carcinoma of the breast. In postmenopausal AUB, endometrial metastasis of breast cancer should be kept in mind, especially in underdeveloped and developing countries where regular breast cancer screening has not been achieved.