Nitrogen oxide (NOx) is an attractive nitrogen source. Electrocatalytic NOx reduction coupled with the conversion of carbon source molecules offers a potential route for sustainable synthesis of valuable nitrogenous organics. This review discusses recent progress on the synthesis of electrocatalytic organonitrogen compounds (such as oximes, amino acids, amines, amides and urea) via C−N coupling from NOx and carbon source. The electrocatalytic performance, catalyst structure and especially reaction mechanism are discussed. Current challenges, catalyst design principles, the understanding on reaction mechanisms, as well as possible strategies for improving reaction selectivity and activity are proposed, which will guide future researches in the electrocatalytic conversion of NOx and carbon source.