Malignant infantile osteopetrosis is a rare hereditary bone disease characterized by defective bone resorption due to impaired osteoclast function or differentiation. This results in generalized osteosclerosis and leads to multiple complications including hematologic failure, neurological compression, skeletal deformities, dental anomalies, and facial dysmorphism. Diagnosis is based on a combination of clinical, biological, radiological, and genetic findings. The only curative treatment for severe forms is hematopoietic stem cell transplantation, which is most effective when performed early. New therapeutic strategies under investigation include gene therapy, immunomodulators, and targeted agents. Prognosis is influenced by the genetic subtype, age at diagnosis, and neurological involvement. Long-term multidisciplinary care is crucial to improve the quality of life of surviving patients.