BackgroundGreen synthesis for nanomaterials, an eco-friendly and sustainable technology, has gained prominence in recent decades, especially in dye removal. The widespread use of toxic organic dyes in various industries has become a significant concern for human health, mainly when these dyes contaminate wastewater. This current study focuses on the prevalent use of hazardous dyes, known for their ecotoxicity, and the challenge of effectively removing these pollutants from wastewater. AimThe primary goal is to achieve a bio-inspired synthesis of zinc oxide nanoparticles using polysaccharides as mediators. This synthesis is designed to enhance the antimicrobial attributes of the nanoparticles and facilitate the photocatalytic degradation of organic dyes. Notably, polysaccharides serve a dual purpose as both a reducing and stabilizing agent for synthesizing ZnO nanoparticles. Significant findingsThe XRD distinctive lattice pattern peaks, such as (1 0 0), (0 0 2), and (1 0 1), affirmed the pure formation of the ZnO structure with a hexagonal wurtzite crystal structure. The chemical composition and product purity of green-produced SB-ZnO NPs were assessed through SEM and XPS analysis. The study then utilized polymer-mediated green-synthesized ZnO NPs for the photocatalytic degradation of Congo red and crystal violet under visible light irradiation. The results demonstrated remarkable photocatalytic activity, with around 88.2% of Congo red dye degradation observed within 80 min of visible light exposure. Notably, Congo red exhibited higher catalytic efficiency compared to crystal violet dye. The antimicrobial activity of SB-ZnO NPs obtained through green synthesis was also investigated. The antimicrobial study revealed the formation of zones against both gram-positive and gram-negative bacterial pathogens. These bioassay metal oxides are recognized for their potential in environmental remediation due to their low cost, stability, efficiency, and minimal environmental impact. The enhanced photocatalytic efficiency of polymer-metal nanocomposites shows significant potential in propelling the utilization of photocatalysts for environmental applications, specifically in wastewater treatment and bactericidal processes.