Congenital melanocytic nevi are defined as an abnormal collection of melanocytes of neuroectodermal origin in an ectopic location and can be categorized as small (<1.5 cm diameter), medium (15–20 cm), or giant (>20 cm diameter). Many definitions of “giant” have been described in the literature including nevi occupying > 1% total body surface area (TBSA) in the head and neck or > 2% TBSA in the trunk, those with a surface area > 100 cm2, or those unable to be excised in a single stage. Most commonly located on the trunk and extremities, nevi begin as pale, hairless brown lesions and develop varying degrees of hyperpigmentation hypertrichosis, verrucosity, and nodularity/ulceration over time. The risk of malignant transformation of melanocytes to melanoma in giant congenital melanocytic nevi is roughly 4% (range 1–40%) and is highest early in life (50% risk of transformation by age 3). Congenital melanocytic nevi are also associated with neurocutaneous melanosis, which involves deposition of melanocytes in the brain and spinal cord and presents with signs and symptoms of increased intracranial pressure, hydrocephalus, spinal cord compression, and seizures. Treatment of giant congenital melanocytic nevi includes noninvasive options such as laser and dermabrasion, which do not eliminate the risk of malignant transformation, and surgical management. Surgical management is preferred in early life to reduce the risk of malignant transformation and psychosocial impact and includes skin grafting, serial excision, and tissue expansion.