Developing transition metal nitrides with unique nanomorphology is important for many energy storage and conversion processes. Here, a facile and novel one‐step approach of growing 3D hierarchical nickel nitride (hNi3N) on Ni foam via nitrogen plasma is reported. Different from most conventional chemical synthesis, the hNi3N is obtained in much shorter growth duration (≤15 min) without any hazardous or reactive sources and oxide precursors at a moderate reaction zone temperature of ≤450 °C. Among possible multifunctionalities of the obtained nanocoral hNi3N, herein the performance in reversible lithium ion storage and electrocatalytic oxygen evolution reaction (OER) is demonstrated. The as‐obtained hNi3N delivers a considerable cycling performance and rate stability as a lithium ion battery anode, and its property can be further enhanced by coating the hNi3N surface with graphene quantum dots. The hNi3N also serves as an active OER catalyst with high activity and stability. Additionally, on the basis of controlled growth under different nitrogen plasma treatment time, the formation mechanism of the nanocoralline hNi3N is outlined for further extension to other materials. The results on time‐ and energy‐efficient nitrogen‐plasma‐based preparation of hNi3N pave the way for the development of high‐performance metal nitride electrodes for energy storage and conversion. Plasma makes nanocorals, via the formation of nickel nitride (Ni3N) nanostructures. Out of the nickel foam surface the nanocorals are induced by a fast and efficient N2 plasma treatment. Functional properties in lithium ion battery and oxygen evolution reaction are demonstrated. Coating of the graphene quantum dots shell further enhances the Li+ storage capability.