We focused to synthesize graphene oxide-polyamidoamine dendrimer, up to 2nd generation, (GO-gen2) via a grafting method and the tethered groups were further covalently functionalized with a nitrogen-rich of an aromatic triazine ring of 5-azacytosine (Aza). Zirconia nanoparticles (ZrO2) has been identified as promising material for removal of AsO33- from water, however, its practical applicability is hindered due to its nanosize. Hence, ZrO2 was successfully decorated through biomolecule assist on GO-gen2-Aza dendrimer. Various amounts of GO-gen2-Aza were used as stable supports to develop the nanocomposites with ZrO2. Then, the adsorption efficiency of highly toxic AsO33- on developed composites was investigated for water treatment. The synthesized GO-dendrimer composites were characterized well before and after adsorption of AsO33- using FTIR, PXRD, SEM, XPS, TGA, TEM and BET analysis. Particle size distribution of ZrO2 revealed the peak top at 28 nm by zeta potential measurement. During synthesis, the GO sheets of composite were laminated by incorporation of ZrO2 nanoparticles. The results of the batch experiments showed that ZrO2 @2%GO-gen2-Aza dendrimer had higher adsorption density of AsO33- than that of other developed forms of dendrimer composites. Langmuir equation well described the adsorption isotherm with the maximum adsorption capacity of 1.075 mmol/g. In addition, the enhanced AsO33- adsorption density on ZrO2 surface of ZrO2@x%GO-gen2-Aza, in which the GO-sheets were delaminated, resulting more ZrO2 was dispersed homogeneously in the GO-sheets for maximum uptake of AsO33- from water, confirmed by PXRD patterns. These results suggested that the developed GO-based dendrimer materials can be utilised for the practical remediation of toxic AsO33- and other similar types of toxic ions, selenite, phosphate and fluoride from the contaminated water.