Cellulose-based materials are good alternatives to petroleum-based materials in the packaging industry, considering their sufficient mechanical properties and sustainability; however, the barrier performances of cellulosic packaging materials against water and water vapor are generally poor due to the hydrophilic nature of cellulose. In this study, a soybean oil-based polymer was synthesized on the surface of several cellulosic materials through an acrylated-epoxidized soybean oil (AESO) reactive coating. The best conversion of the reaction was observed when a suitable reaction temperature, curing time, initiator dosing, and monomer content were selected. Five different types of cellulosic packaging materials were used as substrates for the reactive coating, and their barrier performances were investigated. The improvement in water barrier properties was indicated by the change in water droplet contact angle (CA). The water vapor permeability (WVP) of the substrates was reduced significantly after coating. The water vapor barrier properties of the coating were highly dependent on the tested substrate. A comparison of CA and WVP showed that the change in water vapor barrier did not correspond to surface hydrophobicity.