We report a novel, facile and general approach, in situ nanopressing, to integrate nanoparticles and polymers in a thin film configuration, where both nanoparticles exposure and film robustness are indispensable for applications. By simply pressing silica nanoparticles into a polymer thin film under an external force, we successfully attained a nanoparticles-polymer thin film, where the silica nanoparticles were partly embedded in the polymer thin film. The outstanding characteristic of easy-to-fabricate nanoparticles-polymer thin films combined the properties of both materials, giving excellent antireflective and antifogging properties, as well as enhanced the robustness of composite thin film. This in situ nanopressing may not only provide an alternative to meet the challenge of constructing mechanically robust nanoparticles-polymer thin films that require nanoparticles on the film surface, but also enrich the methodology to integrate nanoparticles and polymers.