Abstract: Nitrogen-doped single-walled carbon nanohorns (N-SWCNHs) can serve as an effective carrier for platinum (Pt) catalysts, which has the potential to improve the electrocatalytic activity of oxygen reduction reaction (ORR) and the operation life of the catalyst. In this work, dahlia-like SWCNHs with N contents ranging from 2.1at% to 4.3at% are controllably synthesized via arc discharge and applied as a carrier of Pt nanoparticles (NPs), denoted as Pt/N-SWCNHs. Pt/N-SWCNHs-2:1 (graphite and melamine with the mass ratio of 2:1) exhibits excellent catalytic activity (onset potential = 0.95 V). The half-wave potential of Pt/N-SWCNHs-2:1 is only reduced by 2 mV after 3000 cyclic voltammetry cycles. This can be attributed to the enhanced dispersion of Pt NPs and the strong electronic interaction between the N-SWCNHs and Pt, facilitated by the optimal nitrogen doping level. The results of this work offer important perspectives on the design and enhancement of Pt-based electrocatalysts for ORR applications, highlighting the critical role of the nitrogen doping level in balancing the catalytic activity and long-term stability.