Ammonia, essential for fertilizers, plastics, and explosives, is traditionally produced via the energy-intensive Haber–Bosch process, which is environmentally harmful. Electrochemical ammonia synthesis offers an eco-friendly alternative, but efficient catalysts for ambient conditions remain challenging. This review discusses decades of research on electrocatalytic ammonia synthesis, focusing on nitrogen reduction (NRR) and nitrate reduction (NitRR) reactions. It highlights theoretical frameworks like Gibbs free energy, Sabatier principle, d-band center theory, and orbital spin states, which guide catalyst design. Key challenges include overcoming high energy barriers and achieving high selectivity and efficiency. Recent advances include defect engineering, alloying, and heteroatom doping, though trial-and-error methods are still common. Theoretical models help predict catalyst performance, while experimental studies validate these insights. NRR involves breaking the N≡N bond and hydrogenating nitrogen, while NitRR reduces nitrate to ammonia. The review emphasizes the importance of understanding reaction mechanisms and optimizing catalysts for efficient ammonia production. Future directions include breaking scaling relations and improving catalyst selectivity. The integration of theory and experiment is crucial for developing sustainable ammonia synthesis methods.Ammonia, essential for fertilizers, plastics, and explosives, is traditionally produced via the energy-intensive Haber–Bosch process, which is environmentally harmful. Electrochemical ammonia synthesis offers an eco-friendly alternative, but efficient catalysts for ambient conditions remain challenging. This review discusses decades of research on electrocatalytic ammonia synthesis, focusing on nitrogen reduction (NRR) and nitrate reduction (NitRR) reactions. It highlights theoretical frameworks like Gibbs free energy, Sabatier principle, d-band center theory, and orbital spin states, which guide catalyst design. Key challenges include overcoming high energy barriers and achieving high selectivity and efficiency. Recent advances include defect engineering, alloying, and heteroatom doping, though trial-and-error methods are still common. Theoretical models help predict catalyst performance, while experimental studies validate these insights. NRR involves breaking the N≡N bond and hydrogenating nitrogen, while NitRR reduces nitrate to ammonia. The review emphasizes the importance of understanding reaction mechanisms and optimizing catalysts for efficient ammonia production. Future directions include breaking scaling relations and improving catalyst selectivity. The integration of theory and experiment is crucial for developing sustainable ammonia synthesis methods.