<p>The rapid rise of fast fashion has intensified concerns about sustainability within the fashion industry. Bacterial cellulose (BC) is increasingly recognized as a promising biomaterial for sustainable applications in textiles and leather; however, dehydrated BC presents several challenges. Its high stiffness and limited dyeing and finishing capabilities, due to a rigid, collapsed structure, reduce its versatility in sectors such as fashion and healthcare. To address these limitations, this study developes a BC-based vegan leather by incorporating polyethylene glycol (PEG) and Disperse Blue 56 dye (DB56) through sustainable technologies, including supercritical carbon dioxide (ScCO₂) and electron beam irradiation (EBI). The resulting BC-based vegan leather exhibits interesting properties, including thermal stability similar to cellulose, enabling compatibility with existing cellulose-based processing methods. Additionally, the modified BC possesses a sponge-like surface morphology, enhances comfort with increased elongation (4.1 ± 0.8%) and tensile strength (27.2 ± 7.5&#xa0;MPa), reduced stiffness (bending modulus of 871.0 ± 126.8&#xa0;MPa), and improved thermal comfort (Q_max of 0.100 ± 0.003 W/cm²). This study also introduced a practical ScCO₂-based dyeing method without additives, catalysts, or mordants, employing PEG as a multifunctional agent for dyeing, plasticization, and EBI-induced cross-linking. By leveraging the unique gas–liquid properties of ScCO₂, this approach addresses the challenges of conventional water-based and liquid-based dyeing for dehydrated BC. Consequently, this work provides a sustainable strategy for advancing eco-friendly BC-based materials.</p> Graphical abstract <p></p>