Aflatoxin contamination seriously endangers food safety and human health, and efficient detoxification technologies are still lacking. In this study, a customized device that combines micro-nano bubbles with ozone (MNBW-O3) was developed to degrade four major aflatoxins (AFB1, AFB2, AFG1, AFG2) in peanut byproduct. MNBW-O3 exhibited superior degradation performance compared with the other five treatments. The operational parameters were systematically optimized, and the optimal conditions were determined to be an outlet pressure of 0.34 MPa, an O3 flow rate of 2.5 L/min, a treatment time of 120 min, and a solid-to-liquid ratio of 12.5 g/L. Under these conditions, the removal rates of AFB1, AFB2, AFG1, and AFG2 reached 87.76%, 77.93%, 79.91%, and 88.56%, respectively. Moreover, the developed MNBW-O3 system demonstrated excellent stability, retaining high degradation efficiency over 12 consecutive reuse cycles. Reactive oxygen species scavenging experiments indicated that •OH, •O2⁻ and O3 participated in degradation, with •OH as the dominant species. Degradation of AFB1, AFB2, AFG1, and AFG2 yielded 37, 14, 19, and 10 products via 18, 6, 7, and 4 pathways, respectively. The primary initial attack occurred at the terminal furan ring, followed by the lactone ring, cyclopentenone, and methoxy group. Theoretical calculations, nutrient analysis, toxicity prediction and cytotoxicity assays confirmed the reaction spontaneity, peanut meal and product safety. This study provides a green, stable and practical detoxification strategy for feed industrial application.