Cases of delayed osteoradionecrosis (ORN) of the anterior skull base have unique management considerations. A 59-year-old woman with a history of basaloid squamous cell carcinoma of the sinonasal cavity with intracranial extension through the anterior skull base developed delayed radiation sequelae of anterior skull base ORN. She underwent an initial endoscopic resection in 2011 with persistent disease that required an anterior craniofacial resection with left medial maxillectomy in 2012. She had a radiologic gross total resection with microscopic residual disease at the histologic margins prompting adjuvant chemoradiotherapy to target volume doses of 66 to 70 Gy with concurrent cisplatin chemotherapy. She subsequently developed an intracranial abscess in 2021 along the anterior skull base that required a craniotomy and endoscopic debridement. Despite aggressive surgical and medical therapy, she had persistent intracranial infections and evidence of skull base ORN. She ultimately underwent a combined open bifrontal craniotomy and endoscopic resection of the necrotic frontal bone and dura followed by an anterolateral thigh free flap reconstruction with titanium mesh cranioplasty. The patient recovered well from a microvascular free-tissue reconstruction without concern for cerebrospinal fluid leak. Anterior skull base reconstruction with free tissue transfer is a commonly utilized method for oncologic resections. Here, an anterolateral free flap was effectively used to treat an anterior skull base defect secondary to a rare indication of skull base ORN.