Uranium is one of the most toxic elements present in the environment and a number of methods have beendeveloped for its extraction. Herein we have demonstrated a new method using magnetic nanoparticles (NPs) that can be used for uranium extraction from water and sea water matrix. Fe3O4 and humic acid(HA) coated Fe3O4NPs with different amount of HA coating were synthesized and uranium sorption fromwater and sea water matrix was demonstrated. It was observed that sorption increases with increase inamount of HA coating. NPs settlement in presence of magnetic field was monitored where only bare Fe3O4 and Fe3O4/HA 1 NPs settles while no settlement was observed for Fe3O4/HA 2 and Fe3O4/HA 3 NPs.Considering both sorption and particle separation from the matrix Fe3O4/HA 1 NPs are the best amongsynthesized ones with maximum sorption capacity of 10.5 mg of U/g of NPs. The results presented herereveal the exceptional potential of magnetic NPs and functionalized magnetic NPs for environmentalremediation of uranium and to extract uranium from sea water on which to the best of our knowledgeno report is available till now.