<p>Spider silk serves as a natural biotemplate for the fabrication of iron oxide microtubes through a two-step process: uptake of iron ions followed by calcination in a furnace. Three distinct iron oxide Fe₂O₃, Fe₃O₄, and FeO were successfully synthesized using this approach. All resulting oxides contain residual carbon (0.27–2.05 wt%), derived from the silk matrix, which significantly enhances their electrical conductivity. These carbon residues not only improve charge transport but also enable the concurrent formation of the various iron oxide phases during calcination. The discharge capacities of Fe₂O₃, Fe₃O₄, and FeO at 0.1&#xa0;C were measured to be 915, 843, and 728 mAh g⁻¹ after 100 cycles, respectively. FeO exhibited the best rate capability, retaining a capacity of 590 mAh g⁻¹ even at a high current rate of 5&#xa0;C. For microbattery applications, spider silk fibers were directly mounted onto a platinum mesh. Following calcination, the resulting Fe₂O₃ microtubes were subsequently coated with PEO to preserve structural integrity during cycling. The PEO-coated Fe₂O₃ microtubes delivered a discharge capacity of 704 mAh g⁻¹ at 0.1&#xa0;C and maintained 97% of this capacity after 50 cycles, demonstrating excellent cycling stability. However, the Coulombic efficiency of the microelectrode remained below 83% due to resistive polarization of the PEO layer. The rate performance of the Fe₂O₃ microtubes showed a moderate decline with increasing C-rate, achieving 589 mAh g⁻¹ at 5&#xa0;C. Electrochemical impedance spectroscopy revealed a gradual loss of interfacial integrity between the PEO electrolyte and the iron oxide microtubes during prolonged cycling, which contributes to the polarization and efficiency limitations.</p>