Electrosynthesis stands out as a promising synthetic strategy to enable the sustainable production of chemical feedstocks and added-value compounds by driving reactions under ambient conditions, using electrons generated from renewable electricity instead of redox reagents. Particularly, electrochemical nitrate reduction (NO3R) has been demonstrated as a sustainable synthetic approach to upgrade nitrate waste into NH3, a very important chemical building block, thus contributing to abate the global nitrogen cycle imbalance. Furthermore, a series of surface-adsorbed reaction intermediates have been identified in the NO3R to ammonia, such as *NO, *NH2OH and *NH2, which exhibit high nucleophilic reactivities and therefore can be coupled with chemical reactions to build C-N bonds. In particular, the electrochemical co-reduction of CO2 and NO3 -has been reported as an attractive route to produce organonitrogen compounds, including urea, methylamine and glycine. Recently, the Zhang and Tan groups have also shown that the *NH2 intermediate generated during NO3R can interact with CO2-derived compounds (i.e. formic acid or CO) to produce formamide. Despite these distinctive methods, current studies on C-N bond formation via NO3R mainly focus on coupling NO3R intermediates with C1-C2 molecules (e.g. CO2, CO, formic acid, oxalic acid). There are a few recent reports on electrochemical NO3R systems which can build C-N bonds in larger organic molecules (i.e. C3+ compounds), such as amino acid and oxime. However, NO3R can make a variety of N-containing byproducts (e.g. N2, NH3, N2O, NO2 -), and therefore the understanding of the complicated NO3R reaction pathways and the controlling of N selectivity towards the desired organonitrogen products remain elusive. Furthermore, the adsorption of N species on the electrocatalyst surface, which plays a central role in tuning the product selectivity, is still largely unexplored for build C-N bonds in C3+ molecules. Inspired by previous reports that the surface-adsorbed *NH2OH is a key intermediate in the NO3R to NH3, herein we report a two-step electrochemical-chemical (EChem-Chem) process for the one-pot synthesis of cyclohexanone oxime with aqueous nitrate as the N source (Figure ). A series of Zn-Cu alloys are prepared to drive the electrochemical NO3R step generate *NH2OH, which can then undergo a chemical reaction with cyclohexanone in solution to produce oxime. Through a combination of experimental and computational studies, we demonstrate that the binding of the reaction intermediates on the electrocatalyst surface plays a central role in the EChem-Chem process. Particularly, we show that weak surface adsorption (e.g. on a pure Zn catalyst) can lead to high potentials for the EChem step, whereas strong adsorption (e.g. on a pure Cu catalyst) can promote this process at lower potentials but results in the complete reduction of *NH2OH to NH3 instead of forming oxime. Notably, we find that a Zn-Cu alloy catalyst with an optimized composition of Zn93Cu7 can efficiently convert aqueous NO3 -(pH 7.0) and cyclohexanone into cyclohexanone oxime with a yield of 97±2% and a Faradaic efficiency (FE) of 27±2% at 100 mA/cm 2 . The NH2OH-mediated reaction pathway and the relationship between oxime-making activity and surface adsorption are supported by in-situ Raman spectroscopy and theoretical calculations. Altogether, this work represents a novel strategy for the one-pot electrosynthesis of cyclohexanone oxime from aqueous NO3 -under ambient conditions, which can upgrade NO3 -and enable sustainable organic synthesis. This study also highlights the potential of producing value-added organonitrogen compounds via electrochemical NO3R, as well as the importance of controlling the binding of surface species for product selectivity in electrocatalysis.