© 2020 Informa UK Limited, trading as Taylor & Francis Group.A new selective, sensitive and rapid method based on magnetic dispersive solid-phase extraction (MDSPE) and the zetasizer system is proposed for trace levels of lead(II) in various water and food samples. In the developed method, the synthesis of a new nanocomposite comprised of diglycolamine-coated magnetic graphene oxide (Fe3O4/GO@DGA) is firstly reported. The nanocomposite was characterised by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR), and the Raman techniques. Several important experimental variables that could affect MDSPE performance, including the pH of the sample, amount of nanocomposite, eluent type and its concentration, and elution time, were optimised. The Fe3O4/GO@DGA nanocomposite carrying lead(II) could be easily separated from real samples simply by applying an external magnetic field. Moreover, Fe3O4/GO@DGA nanocomposite displays selectivity towards lead(II). Due to such features of Fe3O4/GO@DGA nanocomposite excellent dispersibility in water, Fe3O4/GO@DGA seems to be ideal for rapid and cheap determination of lead(II) using methodology based on MDSPE and zetasizer measurement. The high preconcentration factor of 65 allows obtaining detection limits of 0.1 µg L−1 for Pb(II). The method is suitable for the analysis of some food and water.