It is of great importance to control the thickness of catalytic components to enable maximum catalyst utilization and strong catalyst-substrate interaction since electrocatalytic reactions occurring at the interface of catalysts containing one or two-atom thick active layer. Herein, we achieved the ultrathin deposition of 2.5±0.2 nm active layer containing atomically dispersed Mn-nitrogen-carbon (Mn-NC) materials on conductive carbon nanotube (CNT) via solvothermal treatment of formamide and Mn salt, and applied the as-made Mn-NC/CNT composite without pyrolysis directly as catalysts for oxygen reduction reaction (ORR). The atomic dispersion of Mn species in multiple nitrogen surroundings has been confirmed by combining High-angle annular dark-field scanning transmission electron microscopy, X-ray absorption spectroscopy, and X-ray photon spectroscopy. The as-prepared formamide-converted Mn-NC/CNT composite, used for catalyzing ORR, exhibited highly comparable performance in alkaline media relative to that of 20 wt.% Pt/C by showing high onset potential and half-wave potential (E1/2) of 0.91 V and 0.83 V (vs RHE), respectively. Density functional theory (DFT) calculations further suggested that the Mn-N moieties are capable of efficiently accelerating the release of *OH intermediates under more reductive potential, thus exhibiting advanced ORR performance.