Graphene oxide (GO) with high specific surface area was prepared and functionalized with ethylene diamine tetra‐acetic acid (EDTA). The as‐prepared GO and the functionalized one (GO‐EDTA) were characterized using high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), and Raman spectroscopy. The as‐prepared and EDTA funcationalized GO were applied as adsorbent to remove strontium(II) and cobalt(II) from water. The results indicated that the prepared materials are efficient adsorbents for strontium(II) and cobalt(II) removal. The adsorption of CoII and SrII under effects of contact time, temperature, and pH was investigated It is concluded that the maximum adsorption capacities of GO for CoII and SrII were about 168 and 140 mg·g–1, whereas of GO‐EDTA the values were about 197 and 158 mg·g–1, respectively. It is indicated that pH 6 and temperature 40 °C are the best condition for CoII and SrII removal from water. The application of Langmuir and Freundlich isotherms indicated that Langmuir isotherm is best fit for CoII and SrII equilibrium adsorption. Adsorption kinetics were studied by applying pseudo first‐order, pseudo second‐order, and intraparticle diffusion models on the experimental data. The results proved that pseudo second‐order model is the best represented adsorption kinetics. Appling the intraparticle diffusion regressions on the experimental data indicated that intraparticle diffusion involved in adsorption process, which was not the only rate‐controlling step.