This review covers publications on magnetite nanoparticles in polymer matrix, especially in humic acids, which are very interesting, widespread natural polymers. Of special attention was the influence of synthetic conditions on the structure and physicochemical properties of magnetic nanomaterials as well as their potential in environmental applications as sorbents. Nanoparticles of Fe3O4 in polymer matrix as promising materials for environmental applications have been in the focus of a great number of studies due to their properties. The modification of magnetic nanoparticles by humic acids leads to increase the sorption properties of such composites and stabilization of magnetite nanoparticles, inhibiting their agglomeration. Thus, humic acids on the one hand, can be used as effective stabilizers for magnetoactive nanoparticles, and on the other hand, keep their protective properties towards ecotoxicants.