The use of fully mechanized top coal caving technology in modern mines indeed offers high coal production capacity and large daily coal cutting volume on the working face. However, controlling the gas in the upper corner has been a major challenge. To address this issue, a method of gas drainage in the upper corner of the goaf through high-level directional long drilling in the roof has been proposed. In this method, high-level directional drilling is conducted to establish a pathway for gas drainage in the upper corner. The reasonable horizon for the drilling is determined through theoretical calculations and other techniques, which help guide the construction of the drilling. Tests conducted in a large coal mine have shown promising results. The gas concentration in the upper corner has been reduced from the initial range of 0.56–0.98% to 0.42–0.68%, effectively resolving the gas overrun problem. As a result, efficient and safe production of fully mechanized top coal caving face has been achieved. By implementing this gas drainage method, mines utilizing fully mechanized top coal caving technology can enhance safety measures and improve overall productivity.