The oxygen reduction reaction (ORR) critical for electrochemical energy conversion systems suffers from sluggish kinetics and high overpotentials that hinder the efficiency of these technologies. Herein, a curvature-dominated microenvironment modulation strategy is demonstrated to enhance ORR performance via engineering a helical hollow carbon nanotube with embedded sub-nanometer tungsten nitride (W₂N) clusters. This architecture yields optimized electrostatic field distributions and reduced d-band center of W₂N, thereby promoting the enrichment of OH⁻, the adsorption of oxygen, and the desorption of oxygen intermediates ( $\ast$OH). The catalyst shows remarkable ORR activity with a high onset potential of 1.00 V and a half-wave potential of 0.89 V, outperforming both Pt/C and other W₂N-based catalysts. Theoretical calculations verify that the curved support enhances the electron delocalization within the W₂N clusters, regulating the interaction between the catalyst and reactants. Our findings establish a general design principle of curvature-induced microenvironment modulation and offer a new pathway toward designing efficient electrocatalysts for sustainable energy storage applications.