Ion concentration polarization (ICP) has been extensively researched concerning new fundamentals in nanoscale electrokinetics and novel engineering applications. While biomedical and environmental ICP applications have a number of advantages compared to conventional methods, the technique has suffered from the critical limitation of low processing capacity because it has been usually presented in a micro/nanofluidic platform. In this paper, we devised micro fin structures inside a macroscale high-throughput ICP device and successfully demonstrated a stable formation of ICP layer and its performance. Since the fin structures created surface conductive fluidic circumstances and assisted in physically suppressing undesirable electrokinetic vortices generated in this fluidic regime, ICP was stably generated even in this macroscale system. Finally, batch-type droplet ICP preconcentrator and continuous-type ICP separator were introduced as examples for high-throughput millimeter-scale ICP devices using the implanted fin structures.