The advancement of photo-assisted rechargeable sodium-metal batteries with high energy efficiency, lightweight structure, and simplified design is crucial for the growing demand in portable electronics. However, addressing the intrinsic safety concerns of liquid electrolytes and the sluggish reaction kinetics in existing photoelectrochemical storage cathodes (PSCs) remains a significant challenge. In this work, functionalized light-driven composite solid electrolyte (CSE) fillers are systematically screened, and optimized PSC materials are employed to construct advanced photo-assisted solid-state sodium-metal battery (PSSMB). To further enhance the mechanical properties and poly(ethylene oxide) compatibility of the CSE, natural lignocellulose is incorporated, enabling the fabrication of flexible PSSMBs. In situ tests and density functional theory calculations reveal that the light-driven electric field facilitated sodium salt dissociation, reduced interfacial resistance, and improved ionic conductivity (0.1 mS cm