Biochar is a solid substance made by carbonizing biomass. Biochar can be added to the soil and used as a soil conditioner to improve the function of the soil. This study was conducted to investigate the effect of rice hullderived biochar application on the growth, yield and soil physico-chemical properties of the watermelon cultivated under greenhouse. Rice hull-derived biochar was tested with 0 (no treatment), 1,000, 2,000, and 4,000 kg per ha levels. Among the growth characteristics of watermelon harvest season, rice hull-derived biochar application thickened stem diameter and increased fresh weight. The weight of watermelon was the heaviest in 2,000 kg ha -1 rice hull-derived biochar application, and the sugar content of watermelon was 0.3 -0.4°Brix higher than that of control 11.5°Brix. The watermelon yield was the highest at 52,990 kg ha -1 in 2,000 kg ha -1 rice hull-derived biochar application, which was higher than that of control. Changes in soil chemical properties of rice hull-derived biochar application were increased with pH, exchangeable K, Ca and Mg, but available phosphate acid was decreased. The bulk density decreased and the porosity increased with the rice hull-derived biochar application. These results suggest that the rice hull-derived biochar application to the watermelon cultivation area could improve the productivity of watermelon by improving the physico-chemical properties of watermelon cultivation area.