An optimized paste based on short natural cellulose fibers combined with carboxymethyl cellulose at a high dry content (42 wt.%) was implemented as a bio-based material for 3D printing by extrusion. The homogeneous paste exhibited a pronounced thinning behavior and yield stress; it was extruded using a screw extrusion-based direct ink writing system and could easily flow through a small nozzle. The optimized formulation enabled accurate additive manufacturing of parts using a natural air-drying process with or without an ethanol bath. We characterized the anisotropic shrinkage that occurred during the drying of 3D printed parts and proposed a compensation method to account for it. The obtained results emphasized that cellulose had a strong potential to be used as a raw material for 3D printing of cheap, lightweight, robust, and recyclable parts.