Biochar application in the agriculture sector is a practical approach to minimize waste and maintain sustainable farming. However, the information regarding biochar application in tea cultivation is limited and especially rare in field research. In this study, a two-year biochar experiment was conducted in a tea yard subject to tea yield and soil characteristics. According to tea growth, the tea yard for the experiment was divided into weak and normal sectors. Biochar was made from tea processing waste, mainly the twigs. The results showed that biochar application increased tea production by 2.3- and 1.3-fold in the weak and normal sectors, respectively, suggesting that converting tea waste to biochar for soil amendment is beneficial to increasing tea production, particularly in the weak sector. The regression analysis on tea production and soil characteristics revealed that only soil electric conductivity (R2 = 0.6597), soil organic matter (R2 = 0.7024), and soil extractable phosphate (R2 = 0.6547) were positively correlated with tea yield. Therefore, the field experiment of this study improves the understanding of biochar’s agronomic and environmental benefits on plant productivity and soil health.