Abstract The synthesis of hydrazine from the electrooxidation of ammonia (NH 3 ) presents a promising pathway, yet it is hindered by the strong thermodynamic preference for the oxidation of hydrazine. Here, we describe an electrochemistry‐mediated strategy that reverses the thermodynamic order during NH 3 oxidation, enabling sustainable hydrazine production. This process utilizes cyclohexanone (C 6 H 10 O), derived from the electrooxidation of cyclohexanol (C 6 H 11 OH), as a mediator to prevent the over‐oxidation of NH 3 . The in situ generation of cyclohexanone (C 6 H 10 O) at the catalyst interface effectively prevents the over‐oxidation of NH 3 , while cation effect accelerates NH 3 capture during the reaction. Furthermore, the developed manganese (Mn) doped nickel hydroxide electrocatalyst (Mn‐Ni(OH) 2 ) not only improves NH 3 tolerance of the catalyst but also promotes the conversion of nitrogen‐containing intermediates. This scalable approach achieves gram‐scale production at a constant current of 800 mA, offering economic advantages over industrial methods, paving the way for a sustainable transformation of the chemical industry.