In this study, we synthesized dextran (DEX)-coated iron oxide (Fe3O4) and encapsulated it by the anticancer drug cisplatin (CP). This nano-composite functionalized with folic acid (FA) molecules for targeted delivery. These nanoparticles (NPs) were then used as nanocarriers for the targeted administration of CP for treating thyroid tumor cancer. The Fe3O4 NPs were synthesized using a chemical technique. The development of the Fe3O4@DEX-CP-FA nanosystem was achieved using a reverse microemulsion technique. The morphological features of the NPs were characterized using several methods, including dynamic light scattering, atomic force microscopy, vibrating sample magnetometry, high-resolution transmission electron microscopy, and field emission scanning electron microscopy. The docking study has verified that nanoparticles have anti-proliferative effects in thyroid cancer by attaching strongly to molecular targets. The MTT test evaluated the effects of a curative Fe3O4@DEX-CP-FA effect on cancerous and non-cancerous cell lines. The results obtained from the formulation of Fe3O4@DEX-CP-FA revealed the presence of spherical particles with an average size of 107.3 nm, a zeta potential of −28.7 mV, and a polydispersity value of 0.055 mV. Depending on the dose, the nanosystem exhibited cytotoxic effects on thyroid tumor (TT) and normal human thyroid (NHT) cell lines. The study findings indicate that Fe3O4@DEX-CP-FA demonstrated sustained antitumor efficacy while not revealing a harmful impact on normal cells.