Sensing platforms with high interference immunity and low power consumption are crucial for the co-detection of dual oxidative stress biomarkers and clinical diagnosis of periodontitis. Herein, we constructed a bifunctional nanozyme to identify hydrogen peroxide (H2O2) and ascorbic acid (AA) with low crosstalk at zero or low bias voltage. To target H2O2 and AA, Fe(III) meso-tetra(4-carboxyphenyl) porphine (TCPP(Fe)) and Pt nanoclusters were selected as active sites respectively, and titanium carbide nanosheets were additionally introduced as a sensitizer. Due to their highly efficient catalytic properties, self-powered detection of H2O2 without bias voltage and distinguishable AA detection at 0.45 V were successfully achieved. Density functional theory calculations further confirmed the binding sites for target molecules and elucidated the sensing mechanism. On this basis, a dual-channel screen-printed electrode was fabricated to further ensure the discriminative detection of dual biomarkers at the device level. The constructed flexible, low-power consumption sensing platform was successfully applied to raw clinical samples, effectively distinguishing between healthy individuals and patients with varying degrees of periodontitis. This work is expected to provide new insights into the design of highly specific nanozymes and low-power consumption electrochemical sensing systems, which will contribute to the accurate and convenient diagnosis of periodontitis.