Nowadays, biodegradable polymers such as Polybutylene succinate (PBS), Polyhydroxybutyrate (PHB), and Polylactic acid (PLA) are widely used commercially, especially in flexible packaging applications, but these polymers have certain limitations in their properties. The main aim of this study was to develop biodegradable polymer films with improved performance characteristics. This paper focused on developing and enhancing the characterization such as tensile properties, water barrier properties, and biodegradation properties of PBS-PCL(Polycaprolactone), PHB-PCL, and PLA-PCL blends, with the addition of 5wt% of plasticizer [GTA (Triacetin/ glycerol triacetate), a monomeric plasticizer P1, Ultramoll, a polymeric plasticizer P2; and mixed plasticizer P3 (1: 1 mix of P1 and P2)] for flexible packaging application. The plasticized polymer films (thickness 0.25mm) was prepared by injection molding and hot pressing method, and analyze the characterization such as tensile properties (ASTM D882-18 method), water vapor barrier properties (ASTM E96-16 method), and the biodegradation properties in compost (ASTM D5338-15 method), and seawater (ASTM D6991-17 method) medium, and analysis the effect of plasticizers on plasticized polymer blends. The research shows that compared to polymers blends such as PBS, PHB, and PLA, with 20wt% of PCL, there was a significant increase in tensile elongation by 22%,76.6%, and 139.3%, respectively and an increase in biodegradability by 19.5%, 3.6%, and 38.9% in compost medium, and 22.1%, 1.8%, and 41.0% in seawater medium, respectively, with the addition of all three 5wt% plasticizers (Ultramoll), though the tensile strength and water vapor properties were decreased. The plasticizer study shows that plasticized polymer blends using mixed plasticizer (P3) provide the best overall performance enhancement.