In this study, the magnetic composite catalyst, CuFe2O4 modified Co-Al layered double hydroxide supported by alkali-activated N,S-codoped biochar (CFO/CoAl-LDH@K-NSBC) was developed to activate ozone to degrade methylene blue (MB). The MB degradation efficiency of the CFO/CoAl-LDH@K-NSBC/O3 system was 96.30% in 7 min, and it still remained at 92.85% after 5 cycles. Notably, in the pond water matrix, the degradation efficiency only decreased by 6.44% after five cycles, which confirmed its remarkable stability and application prospects. Electrochemical analysis revealed that the comodification of CFO and CoAl-LDH significantly enhanced the charge transfer and catalytic activity of K-NSBC. The results of material characterization and quenching experiments showed that highly exposed active sites, including oxygen vacancies (Ov), Co3+/Co2+, Fe3+/Fe2+, Cu2+/Cu+, pyridinic N, graphitic N and thiophenic S, synergistically drove O3 activation to generate 1O2, ·OH, and ·O2- to participate in MB degradation, among which 1O2 was the main reactive oxygen species. This study provides a novel approach for the preparation of environmentally friendly biochar-based multimetal oxides with high catalytic activity.