Environmental pollution caused by mercury represents a serious threat to human health, especially in areas close to mining activities. Fortunately, there are various techniques to remove mercury from wastewater, such as the use of nanoparticles and porous rocks. In this study, the Bottom Up in situ coprecipitation method was used to impregnate magnetite nanoparticles into pumice, in order to enhance the adsorption capacity of mercury in contaminated water. This method allowed for a homogeneous distribution of nanoparticles in the pumice, turning it into a porous support matrix that improves the adsorption capacity and resistance to deactivation of nanoparticles. The results of the adsorption tests, carried out with mercury solutions at 1 ppm and different contact times, as well as pH modification, demonstrated the effectiveness of the technique. The adsorption capacity was measured, and the adsorption kinetics were analyzed to evaluate the process of mercury removal. Additionally, the adsorption capacity of pumice was evaluated under the same established times for comparison.