Microplastics accumulate to various aquatic organisms causing serious health issues, and they have raised concerns about human health by entering our food chain. The recovery techniques for the most challenging colloidal fraction even for the analytical purposes are limited. Here we show how hygroscopic nanocellulose network acts as an ideal capturing material even for the tiniest nanoplastic particles. We reveal that the entrapment of particles from the aqueous environment is a result of the network’s hygroscopic nature - a feature which is further intensified with the high surface area. We determine the nanoplastic binding mechanisms using surface sensitive methods, and interpret the results with the random sequential adsorption (RSA) model. The microplastic uptake does not rely on any specific interfacial interaction but rather on the water transport behavior of nanocellulose. These findings hold potential for the explicit quantification of the microplastics from different environments, and eventually, provide solutions to collect those directly on-site where they are produced.