The implementation of ultra-high-resolution displays is one of the important technologies for advanced displays. In this paper, an ultra-high-resolution organic light-emitting diode display is implemented without the fine metal mask method, but via a color conversion electrode. A red and green color ultra-high-resolution organic light-emitting diode display with a pixel size of 5 mu m was experimentally realized without changing any aspects of the structure of the OLED display except for the precisely fine-patterned color conversion electrode. Furthermore, nanometer-scale pixel size can be expected through this method. The color conversion electrode is a multilayer structured nanometer thick conductive optical film, and its applicability was confirmed based on a theoretical analysis and optical simulation. The ultra-high-resolution display with color conversion electrode could be a basic technology for the development of advanced high-resolution displays.