[Objective] The effects of different biochar additions on the physical and chemical properties of yellow loam soil, tobacco growth, yield, and output value were analysed in the Chongqing mountainous region to provide technical support for the application of biochar in soil conservation and tobacco production. [Methods] Flue-cured tobacco K326 was used as the experimental material. In 2022—2023, a completely random design was adopted for the tobacco field, and seven treatments of biochar addition were established based on the conventional film ridge cultivation and fertilisation methods. The seven biochar treatments were as follows: zero biochar addition (CK), 750 (T₅₀), 1 500 (T₁₀₀), 3 000 (T₂₀₀), 4 500 (T₃₀₀), 6 000 (T₄₀₀), and 7 500 kg/hm² (T₅₀₀) of biochar. During the study period, soil physical and chemical properties, tobacco agronomic traits, ground and aboveground dry matter, and yield and output values were measured. [Results] ① The application of biochar increased the soil porosity and capillary water capacity. The total porosity and capillary water capacity of soil treated with T₄₀₀ and T₅₀₀ were significantly higher than those treated with CK in the second year of the experiment. ② Compared with the CK treatment, biochar addition significantly increased the contents of available nitrogen, available phosphorus, and available potassium in the 0—20 cm soil profile, and T₃₀₀, T₄₀₀, and T₅₀₀ treatments significantly increased the organic matter content and pH value in the 0—20 cm soil profile, which could effectively alleviate soil acidification. ③ Compared with the CK treatment, the T₃₀₀, T₄₀₀, and T₅₀₀ treatments significantly promoted the growth and biomass accumulation of tobacco and significantly increased the yield and output value of tobacco leaves. Considering the input-output ratio, the T₄₀₀ treatment was optimal for improving the physical and chemical properties of soil, tobacco yield, and output value. [Conclusion] Adding suitable amounts of biochar to tobacco field soil can improve the physical and chemical properties of soil, increase soil cultivability, promote the growth, development, and dry matter accumulation of tobacco plants, and increase the yield and output value of tobacco leaves.