With advances in electronics, the concept of flexible electronics has left traditional designs behind. Many concepts, such as sensors, transistors, soft robotics, data, and energy storage devices have begun to find more widespread and flexible areas of use. From this point of view, using environmentally friendly, abundant, and renewable natural materials that reduce carbon emissions in the production and disposal of these components is the first step toward the concept of sustainable flexible electronics. This review deals with the integration of sustainable natural materials obtained from plant, animal, and bacterial sources into sensors, displays, data storage, power generation, and soft robotic systems, with appropriate examples compiled from the last ten years. In addition, limitations in the use of sustainable materials as flexible electronic components and their potential for use in innovative electronic applications in the future are foreseen.