This research explores the promising potential of Hydroxypropyl Methylcellulose (HPMC) composites enriched with banana fibers, aiming to enhance mechanical and thermal properties for versatile applications, particularly in biomedicine. The study investigates different banana fiber percentages and novel plasticizers effects on these composites, emphasizing the use of glycerol to improve flexibility and processability. Banana fiber-reinforced HPMC films were successfully fabricated with varying loadings (2%, 4%, 6%, and 8%) and were characterized using various analytical techniques. The key findings include improved thermal stability with chemical treatment of banana fibers, the optimal enhancement of tensile modulus at 4% treated banana fiber loading, and the significant improvement in mechanical properties through alkaline treatment. Enhanced adhesion between fibers and matrix, confirmed by SEM analysis, underscores the potential of banana fiber-reinforced composites for engineering applications, such as automotive interiors, packaging, and construction, due to their improved mechanical and thermal properties.