Background:: Due to the limitation of conventional cancer treatment using chemotherapy, the nanoparticle therapeutics have shown enhanced efficacy with alleviating side effects. Objective:: The aim of this study was to prepare the superparamagnetic iron oxide nanoparticles (TC- SPION) for doxorubicin (DOX) loading and delivery. Methods:: Here, we reported a simple green strategy to fabricate T-C-SPION using green tea extract and citric acid. Also, the anti-cancer drug, DOX, was used as a model drug to fabricate DOX-loaded nanoparticles. Results:: The formed T-C-SPION nanoparticles were spherical with a diameter of 23.8 ± 0.8 nm, as confirmed by Transmission Electron Microscopy (TEM). Besides, Dynamic Light Scattering (DLS) revealed that the prepared nanoparticles were water-dispersible and stable while stored in water for 6 weeks. The CCK-8 assay showed T-C-SPION to have a good cytocompatibility using different iron concentrations (10 ~ 120 ug/mL). Furthermore, T-C-SPION had a higher DOX encapsulation efficiency (E_encaps), around 43.2 ± 1.8 %, which resulted in a lagged release profile of DOX, compared to other types of iron oxide nanoparticles using green tea or citric acid alone. Next, cell viability assay indicated that T-C-SPION with a higher E_encaps showed superior and sustained cytotoxicity compared to the control group. Conclusion:: The developed iron oxide nanoparticles synthesized by green tea extract and citric acid in this paper could be considered as a potential drug carrier for cancer therapy applications.