Non-emissive displays that harness ambient light are one of the cornerstones in the area of visually representing the desired object. Among the materials used, therein, electrochromic (EC) materials have shown their great potential, due to their low power consumption, wide-viewing angle, and excellent bistability. These features lead to ease of daily applications like IoT, where traditional famous displays such as LCD and LED cannot easily be adopted. Moreover, EC material-based pixels can dynamically represent RGB colors and contrast within a single pixel, which significantly differentiates them from traditional emissive devices. Displays based on EC materials demand complicated requirements, for example, the design of optically efficient nanostructures, the development of energetically efficient electrochemical systems, and the design of optimized device architectures. However, as these individual aspects and inter-effects are not yet fully understood, a comprehensive understanding of the electrical, chemical, and optical interactions is crucial for advancing device design. In this review paper, an overview of the current developments in non-emissive display technology based on EC materials is provided, and the principles necessary for designing efficient EC display devices are outlined for efficient EC device design.