In this study, the effect of increasing concentrations (0, 0.5, 1, 2% w/w) of potassium sorbate (KS) on the release and antimicrobial properties of edible films based on pullulan (PUL), gelatin (GEL) and their blends (75/25, 50/50, and 25/75) was investigated. The 75/25 and 50/50 polymer mixtures separated into GEL-rich microspheres. The biggest microscopic domains were formed at equal amounts of the polymers. As verified by Fourier-transform infrared spectroscopy, the blending did not cause any chemical changes within the functional groups of PUL and GEL. Release of KS from the PUL- and GEL-rich carriers was primarily due to dissolution and swelling of the polymer matrix, respectively. Consequently, basing on time required for 50% release, the GEL100 film offered at least 2.5 times slower release of KS compared to the PUL100 carrier. The gradual replacement of PUL with GEL tended to decrease KS release rate. The large microspheres of the PUL50/GEL50 films gave release profile similar to the blend system with higher GEL content. The KS diffusion mechanism was found to be Quasi-Fickian. The Weibull models were suitable for the efficient simulation of KS release from the films. At the lowest KS concentration (0.5%), the PUL-rich film-forming solutions (FFSs) tended to have the weakest antibacterial activity, likely due to their high pH values, as well as PUL-KS hydrogen bonding interactions. The FFSs with high levels of KS (2%) exhibited strong inhibitory effects on A. alternata, B. cinerea, P. notatum, S. cerevisiae, and K. apiculata.