The study introduces a 'surface entropy reduction' strategy to design a few-atom-layer metal (FL-M) on high-entropy alloys (HEAs) for the electrocatalytic reduction of nitrate to ammonia (NH₃). The method involves exsolving a component with weak affinity for others, such as silver (Ag), from the HEA surface, forming FL-Ag. This FL-Ag interacts with the HEA substrate, creating geometrically separated active sites for multiple reaction intermediates. The FL-Ag/HEA catalyst demonstrates superior performance, achieving a Faradaic efficiency of 92.7%, an NH₃ yield rate of 2.45 mmol h⁻¹ mg_cat⁻¹, and long-term stability (>200 h). The study highlights the importance of FL-Ag in breaking the scaling relationships inherent in conventional HEAs, allowing for efficient cascade conversion of nitrate to ammonia. The relay catalysis mechanism involves NO₃⁻ reduction to *NO*, followed by *NO* to *NOH*, and finally to NH₃, with FL-Ag facilitating the initial steps and HEA providing necessary H⁺ for the subsequent reactions.The study introduces a 'surface entropy reduction' strategy to design a few-atom-layer metal (FL-M) on high-entropy alloys (HEAs) for the electrocatalytic reduction of nitrate to ammonia (NH₃). The method involves exsolving a component with weak affinity for others, such as silver (Ag), from the HEA surface, forming FL-Ag. This FL-Ag interacts with the HEA substrate, creating geometrically separated active sites for multiple reaction intermediates. The FL-Ag/HEA catalyst demonstrates superior performance, achieving a Faradaic efficiency of 92.7%, an NH₃ yield rate of 2.45 mmol h⁻¹ mg_cat⁻¹, and long-term stability (>200 h). The study highlights the importance of FL-Ag in breaking the scaling relationships inherent in conventional HEAs, allowing for efficient cascade conversion of nitrate to ammonia. The relay catalysis mechanism involves NO₃⁻ reduction to *NO*, followed by *NO* to *NOH*, and finally to NH₃, with FL-Ag facilitating the initial steps and HEA providing necessary H⁺ for the subsequent reactions.