Abstract: Sodium alginate (SA) is difficult to directly electrospin into nanofibers due to its high molecular rigidity and poor chain entanglement capability. In this study, 6-aminopenicillanic acid (6-APA) was employed as a hydrophobic modifier to prepare oxidized sodium alginate-grafted penicillanic acid derivative (OSA-g-APA) with a substitution degree of 29.7% through redox-amination reaction. Subsequently, OSA-g-APA/PVA electrospun composite nanofibers were successfully fabricated using polyvinyl alcohol (PVA) as a spinning aid. Experimental results reveal that chemical modification reduce the critical aggregation concentration (CAC) of OSA-g-APA to 0.440 g/L, enabling self-assembly into stable micelles with an average hydrodynamic diameter of 343.75 nm (PDI=0.39) and Zeta potential of approximately −45.6 mV. Moreover, hydrophobic group grafting not only disrupts intra- and intermolecular hydrogen bonds in SA to enhance molecular chain flexibility, but also strengthens chain entanglement with PVA through hydrophobic association. Although pure OSA-g-APA aqueous solution still fails to produce bead-free fibers, it significantly increases OSA-g-APA content in well-structured OSA-g-APA/PVA composite nanofibers. Furthermore, these composite fibers demonstrate high encapsulation efficiency (EE) and sustained-release characteristics for hydrophobic triclosan (TCA), along with low cytotoxicity and remarkable antibacterial activity. Given the regular fibrous morphology, excellent hydrophobic drug loading/release performance, superior cytocompatibility, and antibacterial properties, OSA-g-APA/PVA electrospun composite nanofibers show promising potential as antibacterial drug delivery systems for functional wound dressing applications.