Oxidative stress overwhelms cellular antioxidant defenses, causing DNA damage and pro-tumorigenic signaling that accelerate cancer initiation and progression. Electron shuttles (ESs) from phytocompounds offer precise redox control but lack quantitative benchmarks. This study aims to give a clearer definition to electron shuttles by characterizing mulberry’s electrochemical capabilities via the three defined ES criteria and deciphering its mechanism against oxidative stress-related cancer. Using double-chambered microbial-fuel-cell power metrics, cyclic voltammetry, and compartmental fermentation modeling, we show that anthocyanin shows a significant difference (p < 0.05) in power density at ≥500 µg/mL (maximum of 2.06-fold power-density increase) and reversible redox cycling (ratio = 1.65), retaining >90% activity over four fermentation cycles. Molecular docking implicates meta-dihydroxyl motifs within the core scaffold in receptor binding, overturning the view that only ortho- and para-substituents participate in bioactivity. In vitro, anthocyanins both inhibit nitric oxide release and reduce DU-145 cell viability dose-dependently. Overall, our findings establish mulberry anthocyanins as robust electron shuttles with potential for integration into large-scale bio-electrochemical platforms and targeted redox-based cancer therapies.