Superconducting niobium nitride wires and ribbons with transverse dimensions down to tens of nanometers were synthesized by annealing NbSe3 nanostructure precursors in flowing ammonia gas at temperatures up to 1000 °C. Their critical temperatures increase with increasing annealing temperatures and reach 9–11.2 K when sintered at 950 °C or above. X-ray diffraction analyses identified Nb4N5 and Nb5N6 phases, dominating at annealing temperatures below and above 950 °C, respectively. Transport measurements show magnetoresistance oscillations at temperatures near the superconducting transition due to vortex-row confinement effects and voltage jumps in current-voltage characteristics at low temperatures attributed to hot-spot behavior.