In this study, we successfully demonstrate single-step industrially scalable reactive extrusion of polylactic acid (PLA)/cellulose nanocrystal (CNC)-based cast films which leads to reduced necking, improved processability, melt strength, and rheological behavior. PLA chains grafted onto CNCs, formed cross-linked gel-like structures of high molecular weight (M-w approximate to 150-245 kDa), with varying grafting efficiency (14%-67%) or gel-fraction yield (16%-69%), depending on the type of compatibilizers used. The reactively processed films show reduction in both oxygen properties (20%-65%) and water vapor barrier properties (27%-50%), along with improved thermomechanical properties. These films finds potential applications for the storage of oil- and dairy-based products, which show shelf lives of similar to 5 months and similar to 2 weeks, respectively, and are within the standard migration limits, as per the set legislations. Therefore, the present study provides a novel, easily processable extrusion -based approach for. manufacturing sustainable PLA/CNC-based green and eco-friendly films with improved recyclability, biodegradability, and nontoxicity for potential applications as food packages on a commercial scale.