Abstract Oxygen reduction reaction (ORR) plays key roles in fuel cells and metal air batteries. Covalent organic frameworks (COFs)‐derived carbons have been utilized for catalyzing ORR. However, the activity and selectivity for these catalysts in the acidic medium is still under improved. In this work, Pt atoms and uniform Pt nanoparticles supported by standing carbons are derived from a three‐dimensional COF. With increasing the contents of Pt ions, the corresponding particle sizes show obvious decrease, and thus resulting in higher catalytic activity. The synergetic roles between Pt atoms and nanoparticles with average sizes of 6.19 nm make catalyst show remarkable activity toward ORR, with onset potential and half‐wave potential of 0.98 and 0.85 V (vs RHE) in the acidic medium, which are 70 and 40 mV more positive than those of Pt/C, respectively. This work provides a new insight for developing COFs in energy storage and conversion systems.