This work investigates the application of origami as the underlying principle to realize a novel 3D printed hand orthosis design. Due to the special property of some origami to become rigid when forming a closed surface, the orthosis can be printed flat to alleviate the most of the post-processing, and at the same time provide rigid support for the immobilized limb in the folded state. The contributions are the origami-based hand orthosis design and corresponding computational design method, as well as lessons learned regarding the application of origami for the hand orthosis design.