The oxygen reduction reaction (ORR) plays a crucial role in the development of cutting-edge technology for clean energy conversion as alternatives to conventional fossil fuel technology. Owing to high cost and scarce supply of current state-of-the-art Pt- and Ir-based catalysts, transition metal nitrides (TMNs) have attracted considerable attention in recent years as a new promising class of electrocatalysts for efficient ORR. Despite the extensive experimental reports, a lack of in-depth understanding of the intrinsic electrocatalytic activity of TMNs poses a serious challenge for systematic development of TMNs based catalysts. Here, we employ density functional theory (DFT) calculations to shed light on the long puzzling area of catalytic activity of TMNs in oxygen reduction reaction. This work demonstrates structure–activity relationships of the nitrides under electrochemical conditions, and offers guidelines on surface modification of TMNs for preparation of efficient catalysts for future generation of energy devices.