Ammonia (NH₃) is a highly important industrial chemical used as fuel and fertilizer. The industrial synthesis of NH₃ relies heavily on the Haber–Bosch route, which accounts for roughly 1.2% of global annual CO₂ emissions. As an alternative route, the electrosynthesis of NH₃ from nitrate anion (NO₃⁻) reduction (NO₃⁻RR) has drawn increasing attention, since NO₃⁻RR from wastewater to produce NH₃ can not only recycle waste into treasure but also alleviate the adverse effects of excessive NO₃⁻ contamination in the environment. This review presents contemporary views on the state of the art in electrocatalytic NO₃⁻ reduction over Cu-based nanostructured materials, discusses the merits of electrocatalytic performance, and summarizes current advances in the exploration of this technology using different strategies for nanostructured-material modification. The electrocatalytic mechanism of nitrate reduction is also reviewed here, especially with regard to copper-based catalysts.