In recent years, the use of preoperative imaging for intraoperative navigation in cranial surgery has increased. These techniques require topographic registration of the patient’s intraoperative position with preoperative images. However, in neuronavigation methods such as CT and MRI, brain shift—resulting from gravity, cerebrospinal fluid drainage, patient positioning, and neuroanesthetic effects—can reduce accuracy. Intraoperative ultrasonography (IOUS) provides real-time imaging and is therefore minimally affected by brain shift, making it more effective for surgical guidance. IOUS enables safe and practical three-dimensional visualization of normal anatomy and a variety of intracranial lesions. After craniotomy, it can be used repeatedly at various stages of the operation. As a dynamic modality, it facilitates not only the assessment of the extent of lesion resection but also the early detection of potential complications—such as hemorrhage—in the vicinity of the surgical field. It also guides real-time surgery during procedures that require ventricular access. The use of IOUS does not materially increase operative time and does not incur additional costs. This article aims to review the applications and methodology of IOUS in cranial surgery.