We demonstrate a simple strategy to enhance the CO₂ reduction reaction (CO₂RR) selectivity by applying a pulsed electrochemical potential to a flat polycrystalline Cu electrode. By controlling the duration and magnitude of the cathodic and anodic pulses, we show that the selectivity for the CO₂RR dramatically improves above 97% faradaic efficiency (FE) and consequently suppresses the competing hydrogen evolution reaction. Selectivity toward methane was found to be up to 83% FE – an unprecedented level of selectivity for a flat polycrystalline Cu electrode. The product output was also found to be tunable toward C₂H₄ and CO depending on the pulse profile applied. Here we investigate three alternate hypotheses and present evidence to disentangle the complex interplay of mass transport, surface coverage, and facet reconfiguration. We conducted CO reduction, rotating disk electrode tests, and in-situ XAS experiments, as well as coupled transport modelling to discern the exact mechanism. Additionally, to further understand the role of dynamic changes in the surface structure we tested CuO, Au, and Mo₂C, which were found to also improve selectivity of products. These results show that pulsing dependence is not unique to Cu, but a more general phenomenon. Our findings provide new insights into the timescales of competing pathways. It also enables an opportunity to further improve the performance of next generation electrocatalyst materials.