A novel formulation system of phytosomes loaded with mitomycin C–soybean phosphatidylcholine (MMC–SPC) complex (MMC-loaded phytosomes) was prepared by a solvent evaporation method combined with a nanoprecipitation technique for the purpose of development of an MMC drug delivery system. The MMC-loaded phytosomes were evaluated by average particle size, zeta-potential, and residual drug-loading content as well as an in vitro drug release profile. Furthermore, in vitro stability tests and in vitro/vivo biological evaluations of the MMC-loaded phytosomes were performed. DSC, FTIR, and XRD demonstrated that MMC interacted physically with SPC within the phytosomes. DLS and ELS described a dispersion with an average particle size of 210.87 nm, a narrow size distribution (PDI 0.251), and a zeta-potential of −33.38 mV. SEM, TEM, and AFM images showed that the MMC-loaded phytosomes were spherical and intact vesicles. In vitro stability tests demonstrated that the average particle size and residual drug-loading content of the MMC-loaded phytosomes had no evident change at different storage conditions. In vitro drug release profiles indicated biphasic behavior with an initial burst release, followed by a subsequent prolonged sustained release. In vitro cytotoxicity assays with H22 cells showed that the MMC-loaded phytosomes had remarkable cytotoxicity. In vivo antitumor effect of the MMC-loaded phytosomes also revealed a dose-dependent and superior curative inhibitory effect on tumor growth without loss of body weight compared to free MMC. Histopathological analysis of specimens taken from tumor tissues indicated that MMC-loaded phytosomes had lethal effect to hepatoma cell. These findings suggested that the MMC-loaded phytosomes can serve as a promising and effective formulation for drug delivery and cancer therapy.