• The particles are almost homo-morphic and are sized between 20-35 nm. • X-ray scanning of a section of FE-SEM image reveals the uniform distribution of Fe, C, O and Au atoms over the nanocomposite surface. • The absorbance rate was evaluated at 570 nm, which represented viability on normal cell line (HUVEC) even up to 1000μg/mL for Fe 3 O 4 @AG/Au . • The IC50 of Fe 3 O 4 @AG/Au were 248, 157, 156, 243, and 198 µg/mL against MOLT-3, TALL-104, J.RT3-T3.5, 32D-FLT3-ITD and Human HL-60/vcr cell lines, respectively. In the current years, conjugated bio-nanomaterials involving magnetic core are interested as promising platform in new generation biological composites. In this regard, we described a novel Au NPs supported Arabic gum (AG) modified magnetic Fe 3 O 4 nanoparticles as a novel anticancer agent (Fe 3 O 4 @AG/Au). The post-synthetically modified biogenic material was analyzed in details over a number of physicochemical methods like, Fourier transformed infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), elemental mapping, X-ray diffraction (XRD) and inductively coupled plasma-optical emission spectroscopy (ICP-OES). In the oncological part of the recent study, the treated cells with Fe 3 O 4 @AG/Au were assessed by MTT assay for 48h about the cytotoxicity and anti-luekemia properties on normal (HUVEC) and luekemia cell lines i.e. MOLT-3, TALL-104, J.RT3-T3.5, 32D-FLT3-ITD and Human HL-60/vcr. The viability of malignant luekemia cell lines reduced dose-dependently in the presence of Fe 3 O 4 @AG/Au. The IC50 of Fe 3 O 4 @AG/Au were 248, 157, 156, 243, and 198 µg/mL against MOLT-3, TALL-104, J.RT3-T3.5, 32D-FLT3-ITD and Human HL-60/vcr cell lines, respectively.