Laryngeal cysts are rare benign lesions, mostly asymptomatic and with a predominant etiology in adults. In children, the failure to diagnose laryngeal cysts is associated with a mortality rate of up to 40% due to the potential for airway obstruction. This article reports the case of an infant who presented with upper airway obstruction and acute respiratory failure. Immediate direct laryngoscopy was performed by the otolaryngology team in the operating room, revealing the presence of a cystic tumor in the vallecula that pushed the epiglottis, leading to almost complete obstruction of the glottic lumen. Microsurgery of the larynx was performed with total excision of the tumor, resolving the laryngeal obstructive condition. Although laryngeal cysts are rare, early diagnosis allows for definitive treatment. This can improve respiratory insufficiency, avoiding prolonged orotracheal intubation, the progression of which can lead to cardiac and respiratory arrest and death.