Recently, there is an increasing interest in research on biodegradable, non‐toxic, and high‐strength biomaterials that can replace plastics, especially in the food industry. In this study, mucilage obtained from Linum usitatissimum seeds is used to develop a natural biodegradable biomaterial by reinforcing it with different concentrations of polydimethylsiloxane (PDMS). The biomaterials produced in the form of films are thoroughly investigated in terms of physicochemical (Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy (SEM), energy dispersive X‐ray spectrum (EDX), atomic force microscopy (AFM), contact angle, and mechanical), biodegradable (in soil and water), and antibacterial properties. SEM‐EDX and AFM demonstrate the homogeneous distribution of PDMS throughout the mucilage matrix. The incorporation of PDMS improves the water solubility of the mucilage composite films, thereby enhancing their strength. It also imparts hydrophobic characteristics to the composite films. Thus, PDMS ensures the high barrier property of the composite films against water vapor. Furthermore, the addition of PDMS increases the antimicrobial properties of the mucilage composite films. The obtained results indicate that the first‐time produced mucilage‐PDMS composite films can serve as an alternative product for food packaging applications.