Cleaning up water contaminants discharged from various industries requires novel materials and approaches. Much effort has been focused on developing such materials including the three-dimensional graphene (3D-G) because of its outstanding physical features. Unfortunately, the relative poor mechanical properties of the most pristine 3D-G limit the recyclability, making them unsuitable for efficient and economic uses. Here, we show a simple and green approach to fabricating 3D-G based composites with various performances largely improved from pure 3D-G. We introduced urushiol monomers which reacted with and polymerized on graphene oxide (GO) sheets, to form 3D-G connected by polymer skeleton. Comparing with traditional 3D-G, the prepared 3D polyurushiol/graphene (3D-PU-G) composite showed remarkable improvement on hydrophobicity, adsorption capacity, mechanical strength and recyclability, which are well suited for water cleanup. By way of example, we have demonstrated the stable and high strength over 20 kPa of 3D-PU-G. The prepared 3D-PU-G also showed efficiently improved adsorption capacity (1.62–1.97 times) from 3D-G for cleaning up various organic solvents and oils from water. Most importantly, our prepared 3D-PU-G composite exhibited highly stable strength and adsorption capacity ever after running for over 100 cycles, whilst those of 3D-G are really poor, i.e. cannot run the 4th cycle to adsorb oil. The study here shows not only the preparation of a 3D-G based composite for water cleanup, but also a general concept to modify graphene for various purposes (e.g. super hydrophobicity for anti-corrosion).