Development of drugs to tackle the ever-increasing cases of cancer and many other diseases including any pandemic is itself challenging. Repurposing existing drugs is an upcoming drug development strategy established for the reuse of existing licensed drugs to ensure accessible, sustainable, and affordable care against cancer. Herein, we presented a nanochemotherapeutic approach based on PEGylated graphene oxide (GO-PEG) loaded with superparamagnetic iron oxide nanoparticles (NPs) and a sustainable natural origin drug, artesunate (ART) to kill cancerous cells. GO-PEG provided a larger surface area to load the dual cargo, iron oxide NPs (∼40%) and ART (∼13%), at a high loading efficiency and simultaneously affected nanotization and crystallinity of the iron oxide NPs. The morphology and internalization of NPs were determined qualitatively and quantitatively by atomic force microscopy (AFM)–Raman imaging and atomic absorption spectroscopy (AAS) analysis, respectively. Furthermore, the loading and unloading of iron reserves were characterized by high-resolution transmission electron microscopy (TEM) images. The loaded iron oxide NPs underwent a pH-triggered release of iron ions, which is higher in acidic pH than in neutral pH. A ∼sevenfold reduction in the IC₅₀ value of ART upon treatment with the designed nanoconjugate is observed. ART is repositioned as a therapeutic drug against cancer cells, and its efficacy is amplified by the Fenton reaction due to iron oxide NPs, as confirmed by a high oxidative stress generated within the cells. The current work suggests that ART and iron oxide NPs loaded on GO-PEG, a biocompatible carrier, are a promising drug–nanoparticle conjugate for cancer treatment.