Lignocellulosic materials can be used for the development of bio-based composites. This study explores the potential of long bamboo fiber bundles extracted directly from bamboo stems using the novel mechanical method and bamboo-based fiber composites (BFC) fabricated using long bamboo fiber bundles and phenolic resins via cold pressing and thermal cure process. The microstructure, mechanical properties, and durability of BFC were evaluated, results being compared with raw bamboo and other commercialized bamboo fiber composites. The mechanical properties of BFC reinforced with 87% (w/w) long bamboo fiber bundles increased more than 50% than those of raw bamboo and were significantly higher than those of other bamboo-based composites. Lower water absorption and thickness swelling were obtained in the case where bamboo fiber bundles with the small fineness. Higher tensile strength was obtained in the case where bamboo fiber bundles with large sizes of bamboo fiber bundles. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40371.