ICONIC (Integrated COnversion of Nitrate and Carbonate streams) pursues the development of a new technology to remediate water ecosystems that have been polluted due to intense agriculture, farming, and CO2 emissions, using electrolysis, to generate globally used chemicals. In particular, ICONIC seeks to convert damaging species responsible of eutrophication and ocean acidification (namely nitrates and carbonates from seawater) into urea, the most important globally produced C-N chemical. Powered by renewables, this offers a path to closing the carbon and nitrogen cycles. ICONIC proposes an integrated electrochemical approach demonstrating, for the first time, the co-electrolysis of carbonates and nitrates into urea selectively, and industrial relevant currents, from seawater using scalable prototypes. Our innovation stems on the accelerated discovery of new catalysts that, based on non-critical raw materials, activate and couple C and N species; their bottom-up synthesis and assembly into mesostructured electrodes to program reaction environments at high current densities; and their implementation into membrane electrode assemblies, all informed by operando characterizations that inform predictive models to guide in the rational design of the catalyst and system. ICONIC leverages interdisciplinary expertise in the areas of chemistry, electrochemistry, materials science, spectroscopies, and engineering, spanning all scales from catalyst design to system-level implementation. ICONIC’s findings would also have positive impact on water-based electrolysis with great decarbonization potential, contributing to their potential operation using abundant seawater.