The widespread use of conventional polyethylene (PE) mulch films in agriculture leads to severe microplastic contamination, degrading soil structure and threatening vital terrestrial biodiversity. This persistent 'white pollution' requires sustainable alternatives. This study addresses this challenge by valorizing recycled cellulose to create fully biodegradable mulch films. Our objective was to synthesize and characterize these green materials, confirming their potential to mitigate plastic pollution while promoting soil health and biodiversity in agro-ecosystems. Films were synthesized via solution casting with glycerol as a plasticizer. Characterization included Scanning Electron Microscopy (SEM), Fourier-Transform Infrared Spectroscopy (FTIR), and tensile testing. Biodegradability was evaluated via a 90-day soil burial test (ISO 20200), and ecosystem impact was assessed in microcosm studies measuring microbial biomass and cress seed germination. The fabricated films exhibited a uniform structure with mechanical properties suitable for field application. The soil burial test demonstrated complete biodegradability, with over 95% mass loss within 75 days. Crucially, microcosm studies revealed zero phytotoxicity, with germination rates identical to controls. Moreover, soil amended with the cellulose film showed a significant increase in microbial biomass compared to soils containing PE fragments, indicating a positive contribution to ecosystem vitality. This research demonstrates that mulch films from recycled cellulose can mitigate plastic pollution while actively supporting soil biodiversity. The findings confirm that these materials provide net benefits to the soil upon degradation, offering a powerful circular economy model for sustainable agriculture that transforms waste into a tool for ecosystem preservation and aligns with global goals for responsible consumption.