Minamata disease is caused by methylmercury, which is produced by microorganisms from inorganic mercury ions, Hg(II), in the aquatic environment. Adsorption is a feasible method to remove Hg(II) from waters, but there are some drawbacks when using conventional adsorbents, for example, tedious solid-liquid separation, slow response, and excessive residual levels of mercury. In this work, a novel spongy adsorbent has been developed for Hg(II) removal via surface functionalization of melamine formaldehyde sponge by glutathione. This material mimics a natural antidote that removes trace heavy metals in the human body. Results show that the functionalized sponge displays a 99.99% removal efficiency for low concentrations of Hg(II) of 10mg/L. As a consequence, the residual Hg concentration is lower than 0.005mg/L, which is slightly below the standard for total mercury in drinking water, of 0.006mg/L, formulated by theWorld Health Organization, and much lower that the discharge regulation standard, of 0.01mg/L, set by the ministry of environmental protection of China. Adsorption kinetic studies indicate that the functionalized sponge has a fast response. Indeed, the adsorption equilibrium can be reached within 10min, and about 80% of total adsorption capacities are reached in 1min. Moreover, the maximum adsorption capacity of the glutathione-functionalized sponge is as high as 240.02mg/g, as shown by adsorption isotherm. Overall our findings disclose the great potential of the developed sponge adsorbent for rapid and efficient removal of Hg(II) from water.