Trinuclear cobalt porphyrin(2.1.2.1) nanobelts have been synthesized. The oxygen reduction reaction (ORR) study reveals that the catalyst featuring a nanobelt cyclic structure with three cobalt active sites favors the 4e- ORR pathway, attaining a selectivity for H2O formation that approaches 100%. This research provides a novel strategy for ORR catalyst design, where the expansive pore structure of the nanobelt complex facilitates substrate binding, while multiple active sites are provided by the multimetallic cavity.