Poly(N-vinylcarbazole) (PVK) was blended with graphene oxide (GO) to form a PVK–GO polymer nanocomposite capable of adsorbing heavy metal from aqueous solutions. The homogenous distribution of GO in the PVK–GO nanocomposite was determined by X-ray photoelectron microscopy (XPS) and attenuated total reflectance – infrared spectroscopy (ATR-IR). The results show that the adsorption capacity of Pb²⁺ by the nanocomposite increased with increasing amount of GO. This phenomenon was attributed to the increasing concentration of oxygen-containing functional groups available in the nanocomposite. Furthermore, the adsorption of Pb²⁺ onto PVK–GO nanocomposite was influenced by pH changes. Higher pHs had a better adsorption capacity than lower pHs, due to changes in the nanocomposite surface properties. The highest adsorption capacity of the PVK–GO nanocomposite for Pb²⁺ was 887.98 mg g⁻¹ and fits well the Langmuir model. This adsorption capacity was achieved using a 10 : 90 wt% ratio of PVK : GO at pH 7 ± 0.5 with a 90 min contact time. The high removal efficiency of this nanocomposite suggests that PVK–GO is effective and can be applied to remove heavy metals from water.