This report details a case of acute idiopathic velopharyngeal insufficiency in a previously healthy eight-year-old girl, presenting with sudden voice alteration and nasal regurgitation following mild respiratory symptoms. Physical examination identified unilateral velar paralysis with open rhinolalia, without additional neurological deficits. Extensive diagnostic evaluation, including nasopharyngoscopy, cerebral and cervical imaging, and infectious serologies, yielded unremarkable findings. In the absence of spontaneous improvement after one week, the patient received a brief course of prednisolone and was referred for speech therapy, leading to full resolution of symptoms within one month. Acute idiopathic velopharyngeal insufficiency is an infrequent condition in pediatric populations, commonly associated with viral infections and typically self-limiting. This case underscores the necessity of ruling out alternative etiologies and maintaining follow-up to confirm the benign trajectory of the disorder.