It is of interest to develop a novel fabrication method of a mineral adsorbent for wastewater treatment to remove the combination of heavy metal ions and refractory organic contaminants. The crosslinking agent stearyl trimethyl ammonium chloride was added into a suspension of montmorillonite and graphene oxide to implement their recombination to fabricated graphene oxide–montmorillonite nanocomposite (GMN). The fabricated nanocomposite was characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller analysis and zeta potential. Results indicated that GMN exhibited a honeycomb texture, providing the chemical reaction site for the simultaneous adsorption of Pb2+ and p-nitrophenol (PNP). Factors including pH value, contact time, contact temperature and GMN dosage in the adsorption process were crucial for both Pb2+ adsorption and PNP adsorption. The optimum adsorption capacities of Pb2+ and PNP onto GMN were 19.39 mg·g−1 and 14.90 mg·g−1 under the condition of pH = 6, contact temperature 55 °C, contact time 60 min and GMN dosage 0.10 g, respectively. Data from experimental studies on simultaneous adsorption was well described by the pseudo-second-order model. The implementation of this work shows that GMN is a promising material for application in the simultaneous removal of heavy metal ions and refractory organic contaminants.