We describe a case of a 14-year-old girl with B-Cell Acute Lymphoblastic Leukemia who developed delayed severe neurotoxicity in her first blinatumomab cycle. Clinical features included encephalopathy and focal neurological deficits. MRI and CSF findings were consistent with immune-mediated neuroinflammation. Following discontinuation of blinatumomab and initiation of dexamethasone therapy, the patient made a complete neurological recovery within five days. This case underscores the potential for delayed onset of blinatumomab-associated neurotoxicity, emphasizing the importance of clinical vigilance beyond the commonly observed early infusion period. Early recognition, prompt cessation of therapy, and initiation of corticosteroids are critical for full neurological recovery.