• Histologically-confirmed ovarian epithelial (including fallopian tube and primary peritoneal) cancer or endometrial cancer

• Molecular tumor board confirms that patient's archival ovarian cancer tumor specimen has been assessed using standard of care genomic profiling and demonstrates CDK4/6 activation features

• Molecular tumor board confirms that patient's archival endometrial cancer tumor specimen has been assessed using standard of care genomic profiling and is of endometrioid histology, has positive hormone receptor expression and lack of Cyclin E gene (CCNE) amplification or retinoblastoma susceptibility gene product (RB) loss

• At least one prior chemotherapy regimen for the treatment of recurrent ovarian or endometrial cancer

• Patients who received chemotherapy must have recovered (Common Terminology Criteria for Adverse Events \[CTCAE\] grade =\< 1) from the acute effects of chemotherapy except for residual alopecia or grade 2 peripheral neuropathy prior to enrollment. A washout period of at least 21 days is required between last chemotherapy dose and study initiation

• Patients who received radiotherapy must have completed and fully recovered from the acute effects of radiotherapy. A washout period of at least 14 days is required between end of radiotherapy and study initiation

• The patient is able to swallow oral medications

• Patient has an Eastern Cooperative Oncology Group (ECOG) performance status of 0-2

• Patient must be willing and able to comply with scheduled visits, treatment plans, laboratory tests, and other study procedures

• Informed consent must be obtained in writing for all patients prior to performing study/screening procedures and prior to registration into the study

• Absolute neutrophil count (ANC) \>= 1.5 x 10\^9/L

• Platelets \>= 100 x 10\^9/L

• Hemoglobin \>= 8 g/dL. Patients may receive erythrocyte transfusions to achieve this hemoglobin level at the discretion of the investigator. Initial treatment must not begin earlier than the day after the erythrocyte transfusion

• Total bilirubin =\< 1.5 x upper limit of normal (ULN). Patients with Gilbert's syndrome with a total bilirubin =\< 2.0 times ULN and direct bilirubin within normal limits are permitted

• Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) =\< 3 x ULN

• Female participants of childbearing potential must have a negative serum pregnancy test within 7 days of the first dose of abemaciclib and agree to use a highly effective contraception method during the treatment period and for 3 weeks following the last dose of abemaciclib