Ingrown toenails are most common among school-age children and adolescents though they can be observed at any age. Causes of ingrown toenails are increased curvature, trauma, and external pressure. Treatment of ingrown toenails can be broadly characterized as conservative and surgical. Conservative treatment can be performed using various methods, such as a gutter splint, dental floss, and cotton. Surgical treatments may be divided into two main approaches; narrowing of the nail plate and debulking of periungual tissues. However, these various conservative and surgical treatments have high recurrence rates, and thus, the author used a permanent surgical method based on the use of a paronychium flap to treat a 15-year-old male adolescent with excessive periungual tissues and curved ingrown toenails who did not improve despite conservative and several surgical treatments over 4 years. Subsequently, toenail shape was maintained without recurrence 22 months after surgery, and there were no complaints of inflammation or pain while walking. This simple surgical method can be performed on patients with advanced ingrown toenails due to excessive periungual tissues and nail curvature and can be expected to have permanent effects.