The work aims to improve the water resistance of polyvinyl alcohol films in a safe and non-toxic manner and blend the κ-carrageenan materials from marine plant with polyvinyl alcohol to partially replace petroleum-based materials as a new packaging material. Firstly, poly(vinyl alcohol) was used as the base material to determine the blended film formulation with optimal mechanical properties by blending κ-carrageenan with different mass fractions of poly(vinyl alcohol) (2.5%, 5%, 7.5%, 10%, and 12.5%). Then, the vanillin/polyvinyl alcohol/κ-carrageenan films were prepared based on the optimal blending formulation after added with different mass fractions of (12.5%, 25%, and 37.5%) vanillin as a cross-linking agent under acidic conditions at pH=2. The chemical structures of the films were investigated by Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD), the microscopic morphologies of the films were characterized by Scanning Electron Microscopy (SEM), the mechanical properties of the films were evaluated based on Tensile Strength (TS) and Elongation at Break (EB), the water resistance of the films was characterized by the hygroscopicity test, Water Vapor Permeation Coefficient (WVP), and Water Contact Angle, and the antimicrobial properties of the films were characterized by the agar disc diffusion test. FTIR spectroscopy showed hydroxyaldol condensation among the aldehyde group of vanillin and the alcohol hydroxyl group of polyvinyl alcohol and κ-carrageenan, proving that cross-linking reaction occurred. When the mass fraction of polyvinyl alcohol was 4%, κ-carrageenan and vanillin were 7.5% and 25% of the mass of polyvinyl alcohol, respectively, the tensile strength of the blended film reached 44.02 MPa. Compared with the pure poly(vinyl alcohol) film, the moisture adsorption (100% RH) and water vapor transmission coefficient were improved by 17.91% and 15.18%, respectively. Antimicrobial circle experiments showed that the addition of vanillin improved the antimicrobial properties of the blended films. In summary, the addition of vanillin improves the water resistance, mechanical properties and antimicrobial properties of the polyvinyl alcohol/ κ-carrageenan blended films, overcoming the drawbacks of poor water resistance of polyvinyl alcohol films and expanding their applications.