A novel and specific drug delivery for in vitro cancer targeted are developed successfully by a simple one-step method. A CoFeO@Methionine core-shell nanoparticle was prepared by the reflux assay which amino acid in the surface makes ferrite biocompatible, enhances its chemical stability, and improves the drug-loading capacity. The synthesized nanoparticles were characterized using FTIR, TGA, XRD, SEM, TEM, and VSM which coating amino acid on the surface of CoFeO was confirmed by XRD and TGA. The appearance of a new peak for C≡N confirms the formation of Letrozole-loaded carrier in the FTIR. The vibrating sample magnetometer of both bare CoFeO and Methionine-coated CoFeO nanoparticles exhibited room-temperature superparamagnetic behavior with a saturation value of 46 emu/g and 16.8 emu/g, respectively. The morphology and size of samples were characterized by SEM and TEM that the average size of the particle was around 28-29 nm. The loading of Letrozole and the effect of pH (5, 7.4) on the release behavior of the carrier was studied. The result of the drug release in pH is equal to 5 was about 88% which higher than pH is equal to 7.4. Also, the preparation had been evaluated for determining its cytotoxicity using MCF-7, MDA-MB-231, and MCF10A cells as an in vitro model, and the result vitro experiments showed that CoFeO@Methionine could significantly reduce cancer in cells model. These results demonstrate that core-shell nanoparticle was prepared is biocompatible and have potential use as drug delivery.