Postoperative pneumocephalus (PNC) is very common in craniotomy surgeries. It can be asymptomatic or if present in more volumes can cause symptoms such as lethargy, headache, confusion, or even severe neurological deficit. Treatment of pneumocephalus with supplemental oxygen via facemask is a common neurosurgical practice. There is not much evidence of use of high-flow nasal oxygen therapy (HFNOT) for the management of PNC. Here we report a case of an 8-year-old boy with postoperative symptomatic pneumocephalus, which resolved with the application of supplemental oxygen via a high-flow nasal cannula with 30 L/min flow and FiO2 of 0.7 over 72 hours. High-flow nasal oxygen therapy can be an effective modality of treatment for postoperative PNC with added advantages of patient comfort and maintenance of warmth and moisture of the respiratory tract.