As one of the most important chemicals and an energy carrier, synthetic ammonia has been widely studied to meet the increasing demand. Among various strategies, electrochemical nitrogen reduction reaction (e-NRR) is a promising way because of its green nature and easy set-up on large-scale. However, its practical application is extremely limited because of the very-low production rate, which is strongly dependent on the electrocatalysts used. Therefore, searching novel efficient electrocatalysts for e-NRR is essential to promote the technology. In this review, it highlights the insights on the mechanism for the NH₃ electrochemical synthesis, recommend a reliable protocol for the ammonia detection, and systematically summarize the recent development on novel electrocatalysts, including noble metal-based materials, single-metal-atom catalysts, non-noble metal, and their compounds, and metal-free materials, for efficient e-NRR in both experimental and theoretical studies. Various strategies to improve the catalytic performance by increasing exposed active sites or tuning electronic structures, including surface control, defect engineering, and hybridization, are carefully discussed. Finally, perspectives and challenges are outlined. It can be expected that this review provides insightful guidance on the development of advanced catalytic systems to produce ammonia through N₂ reduction.