To evaluate the potential of the rGO-Co₃O₄-Pt/SPEs platform for in vivo applications, we investigated its ability to monitor H₂O₂ levels in an animal model of DOX-induced cardiotoxicity. Figure demonstrate that the rGO-Co₃O₄-Pt-modified electrode detected significantly higher currents in DOX-treated mice compared to both control mice and the bare electrode, indicating elevated H₂O₂ levels due to increased oxidative stress. Control mice showed minimal current responses, confirming low H₂O₂ levels and the selectivity of rGO-Co₃O₄-Pt/SPEs. The results demonstrate that the rGO-Co₃O₄-Pt/SPEs platform effectively detects elevated oxidative stress levels in DOX-treated mice, confirming its high sensitivity and selectivity for monitoring oxidative stress in vivo. This highlights its potential for applications in studying ROS-related pathologies and diagnostics. The results show a strong correlation between the performance of the proposed rGO-Co₃O₄-Pt/SPEs biosensor and the traditional fluorescence-based method for detecting ROS in cells and tissues. This consistent alignment confirms the biosensor as a dependable and sensitive tool for monitoring oxidative stress. Its ability to deliver results comparable to the traditional fluorescence assay underscores its potential for wider use in ROS research and diagnostics.