Orthoses with electronic functions have emerged as a promising medical product in response to the increasing demand for rehabilitation training, therapy assistance, and health monitoring. However, fabricating this “smart orthosis” often requires long development cycles and exorbitant prices. We introduce E-Orthosis, an integrated fabrication approach with construction toolkits for healthcare professionals to quickly embed electronics in off-the-shelf orthoses with customized functions cost-effectively and time-efficiently. Specifically, we develop components with magnets and pogo pins to support rapid attachment and sustainable use, and textile-based electrodes with snap installation to improve the wearing experience. We also provide a circuit iron tool to apply circuit traces on complex surfaces of orthoses directly and a hot punch tool to embed magnet ports and electrodes. Three application examples, technical evaluations, and expert reviews demonstrate the functionality of E-Orthosis and the potential for democratizing rapid-developed and low-cost smart orthoses for patients.