<p>Electrocatalytic nitrate-to-ammonia conversion offers dual environmental and sustainable synthesis benefits, but achieving high efficiency with low-cost catalysts remains a major challenge. This review focuses on cobalt-based electrocatalysts, emphasizing their structural engineering for enhanced the performance of electrocatalytic nitrate reduction reaction (NO₃RR) through dimensional control, compositional tuning, and coordination microenvironment modulation. Notably, by critically analyzing metallic cobalt, cobalt alloys, cobalt compounds, cobalt single atom and molecular catalyst configurations, we firstly establish correlations between atomic-scale structural features and catalytic performance in a coordination environment perspective for NO₃RR, including the dynamic reconstruction during operation and its impact on active site. Synergizing experimental breakthroughs with computational modeling, we decode mechanisms underlying competitive hydrogen evolution suppression, intermediate adsorption-energy optimization, and durability enhancement in complex aqueous environments. The development of cobalt-based catalysts was summarized and prospected, and the emerging opportunities of machine learning in accelerating the research and development of high-performance catalysts and the configuration of series reactors for scalable nitrate-to-ammonia systems were also introduced. Bridging surface science and applications, it outlines a framework for designing multifunctional electrocatalysts to restore nitrogen cycle balance sustainably.</p>