To address the challenge of treating azo dye wastewater, this study prepared biochar-chitosan composite microspheres (CSBC) via the sol-gel method and systematically investigated their performance and mechanism in activating persulfate (PDS) for the degradation of methyl orange (MO). The results indicate that at a biochar pyrolysis temperature of 700°C and a BC/CS mass ratio of 2:1, the CSBC/PDS system achieved a 92.02% degradation rate of MO within 60 minutes, with a reaction rate constant (Kobs) of 3.720 h?1, significantly outperforming individual biochar (53.75%) or chitosan (37.76%). Characterization analyses revealed that CSBC combines the porous framework of biochar with the active functional groups (amino and hydroxyl) of chitosan, forming a synergistic catalytic interface. Quenching experiments and electron paramagnetic resonance (EPR) confirmed that the non-radical pathway dominated by singlet oxygen (1O?) is the primary degradation route, supplemented by a direct electron transfer mechanism. Practical application in real water bodies demonstrated that the CSBC/PDS system maintained over 80% MO removal efficiency in Yangtze River water, Minzhu Lake water, and tap water, with a degradation efficiency of 86.78% within 60 minutes in a continuous-flow reactor. This study provides an efficient and green solution for the treatment of dye wastewater.