AbstractThe development of solid‐state electrochromics (EC) represents an emerging challenge towards effective integration with other optoelectronic units, such as the EC‐organic light‐emitting diode devices (EC‐OLEDs). By a simultaneous or independent control of optical contrast (EC function) and OLED emission upon electrical activation, these fascinating systems are capable of adaptively modulating solar radiation and display lighting. Here, we report a flexible ECOLED on a single‐plastic substrate demonstrating how the rational design of a highly efficient and durable solid‐state EC cell enables an increase of overall performances and the integration with OLED on larger area and flexible substrate. The resulting device shows high transparency and optical contrast (ΔT650nm = 60%), with lower operating voltages (0.5–3 V), faster coloring/bleaching switching times (5–10 s), and enhanced stability (1000 switching cycles) if compared to similar systems. The OLED unit reveals a luminance of 1000 cd m−2 (at 10 mA cm−2) and a current efficiency of about 10 cd A−1, making it suitable for both display and lighting applications. These results can represent a novelty in the field of next‐generation smart windows and transparent displays, including all technologies based on see‐through OLED displays, electronic devices for augmented reality, lighting panels and smart glasses.