Flexible electronics, as an essential branch of wearable electronics, have recently attracted extensive research owing to their wide range of applications in healthcare tracking, human-machine interface, wireless communication, or energy generator. These electronic devices are flexible and small in size to add on clothing or skin. However, this also creates signal acquisition, processing, and noise suppression difficulties. To reflect different requirements, new materials, geometrical designs, and manufacturing strategies have been developed to optimize mechanical-electrical properties and device performance. In this paper, the critical progress in flexible electronic development over the last two years is selectively reviewed from materials and fractal structures perspective. Significantly, the meaning of the fractal structures for the devices and applications are analyzed in detail. Finally, this review summarizes the challenges and opportunities that fractal designs can become a key to widespread development and adoption for future research.