Electrochemical ammonia synthesis (EAS) offers a promising alternative to the Haber–Bosch process due to its energy efficiency, low carbon emissions, and environmental benefits. However, the competing hydrogen evolution reaction (HER) significantly limits the yield, selectivity, and current efficiency of ammonia production. Active hydrogen (H*) plays a dual role in EAS: it is a key intermediate in hydrogenation and deoxygenation processes and also contributes to HER. Therefore, controlling H* generation and consumption is essential for improving EAS performance. This review provides a comprehensive overview of H* in EAS, including its generation, conversion, identification, and quantification protocols. It summarizes the role and control strategies of H* in EAS, with a focus on regulating H* generation and consumption to enhance activity, selectivity, and Faradaic efficiency. The review also discusses remaining challenges and future perspectives in EAS technology. Key strategies for controlling H* include inhibiting the Volmer step, inhibiting the Heyrovsky/Tafel step, generating H* on demand, and promoting its generation and consumption. Various methods, such as modifying catalysts, using proton scavengers, and designing tandem catalysis systems, have been explored to effectively regulate H* and suppress HER. Additionally, membrane electrode assembly (MEA) systems and proton shuttle systems have been proposed to improve H* supply and enhance ammonia synthesis efficiency. The review highlights the importance of balancing H* production and consumption to achieve high selectivity and efficiency in EAS. Overall, effective regulation of H* is crucial for advancing EAS technology and achieving sustainable ammonia production.Electrochemical ammonia synthesis (EAS) offers a promising alternative to the Haber–Bosch process due to its energy efficiency, low carbon emissions, and environmental benefits. However, the competing hydrogen evolution reaction (HER) significantly limits the yield, selectivity, and current efficiency of ammonia production. Active hydrogen (H*) plays a dual role in EAS: it is a key intermediate in hydrogenation and deoxygenation processes and also contributes to HER. Therefore, controlling H* generation and consumption is essential for improving EAS performance. This review provides a comprehensive overview of H* in EAS, including its generation, conversion, identification, and quantification protocols. It summarizes the role and control strategies of H* in EAS, with a focus on regulating H* generation and consumption to enhance activity, selectivity, and Faradaic efficiency. The review also discusses remaining challenges and future perspectives in EAS technology. Key strategies for controlling H* include inhibiting the Volmer step, inhibiting the Heyrovsky/Tafel step, generating H* on demand, and promoting its generation and consumption. Various methods, such as modifying catalysts, using proton scavengers, and designing tandem catalysis systems, have been explored to effectively regulate H* and suppress HER. Additionally, membrane electrode assembly (MEA) systems and proton shuttle systems have been proposed to improve H* supply and enhance ammonia synthesis efficiency. The review highlights the importance of balancing H* production and consumption to achieve high selectivity and efficiency in EAS. Overall, effective regulation of H* is crucial for advancing EAS technology and achieving sustainable ammonia production.