A Glass Fiber Reinforced Polymer (GFRP)-confined Bamboo-reinforced fine aggregate Concrete composite Rod (GBCR) is proposed, as an alternative for the thin-walled steel tubes in compressive and bending load-bearing components. To investigate the mechanical properties of GBCR and the synergistic interaction among different materials, a comprehensive experimental study was conducted. The influence factors on the mechanical behaviour of GBCR are investigated by conducting axial compression tests of twelve short GBCR compressing-resistant (SGC) specimens and seven long ones (LGC specimens), and bending tests of ten long GBCR bending-resistant (LGB) specimens. The SGC specimens fail in an axial compression mode characterized by GFRP tube expansion cracking and concrete crushing. The LGC specimens experience instability under axial compression, and brittle fracture is observed in the LGB specimens. The mechanical behaviour of GBCR is influenced by the material composition, bamboo content, concrete compactness, bamboo arrangement direction, and bamboo-reinforcement defects. GBCR specimens with a bamboo content of approximately 20% exhibit a good load-carrying capacity that matches or even exceeds that of the thin-walled hollow steel tube specimens. Furthermore, the LGC specimens show excellent elastic recovery capabilities. Based on the experimental results, a formula for estimating the ultimate axial compressive bearing capacity of GBCR is established.