To understand the formation process of ordered Au nano-ring arrays (NRA), a series of factors—including etchant gas and flow rate, chamber pressure and RF power—were systematically studied and a set of optimum parameters were deduced to fabricate this interesting structure. With plenty of active sites previously reported, a new role of ordered Au NRA is unlocked in this work. The ordered Au NRA could perform the electrochemical removal of rhodamine 6G (R-6G) at a high concentration in seawater within 12 min and complete discoloration within 9 min, which demonstrates ~7 times efficiency improvement from previous studies. The nanostructured surface also makes the ordered Au NRA a good substrate material in R-6G sensing using surface-enhanced Raman spectroscopy, which performs with better accuracy than the ultraviolet–visible light technique.