<p>This study investigates the fabrication and characterization of short carbon fiber-reinforced epoxy composite honeycomb structures with moderate to high strength, featuring triangular (T), hexagonal (H), and square (S) core designs. These structures are produced using direct ink writing (DIW) 3D printing with customized epoxy inks formulated with 10–40 wt% carbon fibers and rheological modifiers to achieve desired shear-thinning and yielding properties for precise printing of complex geometries. This fabrication approach allowed for mold-free fabrication of bioinspired honeycomb structures with variable core geometries and cell sizes, achieving superior surface finish and dimensional accuracy compared to 3D-printed continuous carbon fiber reinforced thermoplastic composites. The mechanical performance of these structures was engineered by altering geometric configurations, material compositions, and infill densities (30–50%). In-plane compressive tests showed stiffness improvements of 59%, 43%, and 47%, and strength gains of 106%, 93%, and 162% in triangular, hexagonal, and square honeycomb cores, respectively, as infill density increased from 30 to 50% for ink with 40 wt% carbon fiber. Specific strength followed similar trends. Comparisons with scaling laws indicated comparable strength for triangular cores, lower strength for square cores, and higher strength for hexagonal cores, surpassing previously reported values. This study demonstrates the potential of DIW combined with engineered inks to fabricate advanced composite honeycomb cores with tailored properties, offering promising applications in lightweight, high-performance structural designs.</p>