The dysregulation of dopamine (DA) and hydrogen peroxide (H₂O₂) is critically implicated in neurological and psychiatric disorders, which highlights the urgent need for sensitive and selective in-situ monitoring. Current electrochemical sensors, however, are often limited by the structural and electronic constraints of conventional nanomaterials. Herein, we present an atomically dual-atom catalyst (DAC) of paired Pt atoms embedded in an N, O-doped carbon framework (Pt₂-N₄O₂/CB), which functions as a remarkably durable and synergistic active center. In situ X-ray absorption near-edge structure (XANES) uncovers the dynamic interaction between electronic structure and catalytic pathway at the coupled Pt–O–Pt site. Density functional theory calculations further reveal the strong electronic interaction between the catalytic Pt₂ center and adjacent N/O atom, which alters the electronic states, leading to an upshifted d-band center and weakened binding strength for reaction intermediates, thus boosting the biosensing performance. Compared to single-atom Pt catalyst (Pt-N₂O₂/CB), the dual-atom Pt₂ catalyst (Pt₂-N₄O₂/CB) achieves 1.37-fold and 6.79-fold enhancements in the detection sensitivity for DA and H₂O₂, respectively. Furthermore, the Pt₂-N₄O₂/CB electrode also exhibits outstanding operational stability, retaining over 87% of its initial activity after 600 h. This work provides the potential of DAC as an effective platform for advancing electrochemical sensing and biomedical diagnostics.