Primary ovarian lymphoma is a rare disease, and its definition is still controversial. Many cases of primary ovarian lymphoma are diagnosed as diffuse large B-cell type, whereas the precursor lymphoblastic type is extremely rare. Herein, we describe a case of precursor B-cell lymphoblastic lymphoma of the ovary that was successfully treated with surgery and chemotherapy. A 19-year-old woman presented ovarian tumors and paraaortic lymphoadenopathy, which were suggestive of advanced ovarian cancer. Exploratory laparotomy and right salpingo-oophorectomy were performed, and the diagnosis of precursor B-cell lymphoblastic lymphoma was established. The patient was treated with a combination of chemotherapy and is currently disease-free 1 year after surgery. To our best knowledge, this is the fourth reported case of precursor lymphoblastic lymphoma of the ovary.