The increasing environmental concerns of synthetic polymers, particularly their non-biodegradability and pollution, have led to a search for sustainable alternatives. Multidrug antibiotic-resistant microorganisms are increased in number due to the continuous use of synthetic antibiotics. Biopolymers, such as polyhydroxybutyrate (PHB), offer a promising solution to petroleum-based plastics and synthetic antibiotics. Bacillus chungangensis bacteria was isolated from the soil samples of the Western Ghats of Tamil Nadu, India, and studied for the synthesis of PHB using various carbon sources including the waste sugarcane bagasse to enhance both sustainability and cost-efficiency. The antimicrobial efficiency of biopolymer from Bacillus chungangensis was evaluated against multiple human pathogens. It exhibited excellent antibacterial activity compared to the standard antibiotics against a range of pathogens such as Escherichia coli (25 mm), Pseudomonas aeruginosa (24 mm), Proteus vulgaris (20 mm), Shigella flexneri (20 mm), Pseudomonas fluorescens (23 mm), Klebsiella pneumonia (15 mm) and Staphylococcus aureus (15 mm). The standard antibiotics gentamycin, tetracycline, methicillin, and kanamycin did not produce the zone against Klebsiella pneumonia. Similarly ampicillin and methicillin not produced the zone of inhibition against Pseudomonas aeruginosa and Pseudomonas fluorescens. These results suggest that biopolymers produced by Bacillus chungangensis are highly effective antibacterial agents against human pathogenic bacteria.