Multifunctional polymer scaffolds with mechanical support, biocompatibility, and antimicrobial activity are key for next-generation biomedical materials. We report the fabrication of electrospun nanocomposite fibers made from polycaprolactone (PCL), starch, and mesoporous aluminum oxide nanoparticles (n-Al₂O₃). Nanoparticles (11 ± 4 nm) were synthesized via a sol-gel method, predominantly comprising γ- and α-Al₂O₃ phases. Four fiber systems were fabricated by side-by-side electrospinning: PCL, PCL/starch, PCL/n-Al₂O₃, and PCL/starch/n-Al₂O₃. SEM analysis confirmed uniform and bead-free fibers in all formulations. Tensile tests showed that the incorporation of starch and nanoparticles improved the mechanical performance compared with neat PCL. In particular, PCL/starch/n-Al₂O₃ fibers exhibited increases of 404% in Young’s modulus and 102% in elongation at break. In PBS, starch and n-Al₂O₃ enhanced hydrophilicity and accelerated weight loss, with PCL/starch/n-Al₂O₃ showing the highest mass loss. Antibacterial tests indicated that only fibers with nanoparticles could inhibit Staphylococcus aureus and Escherichia coli, with PCL/starch/n-Al₂O₃ showing a major effect. Although n-Al₂O₃ increased cytotoxicity toward NIH-3T3, starch mitigated this effect, and the ternary scaffold showed no detectable cytotoxicity. Moreover, PCL/starch/n-Al₂O₃ exhibited non-hemolytic behavior, enhanced fibroblast migration, and wound-healing-related protein expression. Overall, side-by-side electrospun PCL/starch/n-Al₂O₃ scaffold exhibited showed improved mechanical, biological, and antibacterial properties, supporting its potential as a wound-dressing material.