Abstract Background Biochar is mainly used to enhance soil fertility, microbial activity, improve plant performance and reduce disease incidence. Methods A greenhouse experiment was designed to investigate the response of biochar on rhizosphere soil chemical properties, enzyme activity, microbial communities, and sugarcane Pokkah boeng disease (PB). Two sugarcane varieties Zhongzhe 9 (Z9) and ROC22, susceptible/resistant to PB, were cultivated and treated with: no biochar, 15 t ha−1 biochar, and 30 t ha−1 biochar. Results The amendment of 30 t ha−1 of biochar (B2) significantly improve soil pH by 1.50% and 9.61% compared with that of B1 and B0, followed by 0.51% increase by 15 t ha−1 of biochar (B1) compared with that of control (B0). The application of 15 t ha−1 biochar significantly increased available phosphorus (AP) and ammonium nitrogen (NH4 +–N) by 209.93 mg kg−1 and 12.1 mg kg−1, while the application of 30 t ha−1 of biochar significantly increased 241.04 mg kg−1 of available potassium (AK) (P