Background <p>Only isolated occurrences of neonatal Jk^a hemolytic disease have been identified, and no cases of Jk^a hemolytic disease combining fetal and neonatal alloimmune thrombocytopenia (FNAIT) have been reported. The majority of medical professionals lack sufficient knowledge regarding Jk^a hemolytic disease, which could result in missed diagnoses and early misdiagnoses.</p> Case presentation <p>In this study, a case of a male newborn with extreme anemia and thrombocytopenia is reported. The newborn and his mother were identified as blood groups O RhD + and Jk(a + b+), and O RhD + and Jk(a-b+). Anti-Jk^a was identified in the plasma of both the mother and newborn. Thrombocytopenia and upper gastrointestinal bleeding were observed in the newborn, and both mother and newborn tested positive for platelet antibodies. The extreme anemia and thrombocytopenia were successfully treated with red cell transfusions and immunoglobulin.</p> Conclusion <p>Co-existence of neonatal Jk^a hemolytic disease and FNAIT is very rare in newborns with significant clinical manifestations. Early diagnosis and timely treatment are crucial for improving patient outcomes.</p>