Water desalination and purification are critical to address the global issue of the shortage of clean water. Forward osmosis (FO) desalination is an emerging low-cost technology for clean water production from saline water. The lack of a suitable draw agent is one of hurdle for the commercialization of FO desalination technology. Recently, the thermoresponsive hydrogel has been demonstrated to be a potential draw agent for the FO process. However, the commonly used hydrogel powder shows a much lower flux than other kind of draw agent such as inorganic salts. In this work, a hydrogel-polyurethane interpenetrating network (HPIPN) with monolith formwas prepared by controlling the radical polymerization of the monomers (N-isopropylacrylamide and sodium acrylate) in the macropores (~400 mm) of commercial polyurethane foam (PUF). These HPIPN composites show a flux as high as 17.9 LMH, which is nearly 8 times than that of hydrogel powders (2.2 LMH). The high flux is attributed to the 3-D continuous hydrogel-polyurethane interpenetrating network, which can effectively enhance the water transport inside the monolith.