The interactions between water and polymers represents a research field of great interest. Interplay between water and biopolymers has a fundamental function in biochemical processes, as well as an influential characteristic in materials science and industry caused by the interaction of commercially used polymers with water. The investigation of the properties of water-polymer systems has often been performed using vibrational spectroscopy techniques (infrared or Raman). In contrast, the potential of near-infrared spectroscopy (NIRS, 12,500–4000 cm−1; 800–2500 nm) has received little attention in studying this problem. Although NIRS offers exclusive opportunities for the study of molecular structures and their interactions. Unique information from the overtones and combination bands is accessible with this technique. NIRS is also very well suited for the analysis of aqueous systems, as both the bands of water and the polymer can be reliably acquired in a range of concentrations, in a more straightforward manner than it is possible in MIR spectroscopy. In this study the polymer-water interactions of polymers with diverse hydrophilicity were investigated by NIRS. On the one hand, commercially used hydrophobic polymers: polytetrafluoroethylene (PTFE), polypropylene (PP), polystyrene (PS), polyvinylchloride (PVC), polyoxymethylene (POM), polyamide 6 (PA) and on the other hand biopolymers: lignin, chitin and cellulose, were analyzed. The polymer-water mixtures were examined in a mass concentration range of 1–10% water. Analysis and interpretation of the NIR spectra included cluster analysis methods, difference spectroscopy, Multivariate Curve Resolution (MCR) and Two-Dimensional Correlation Spectroscopy (2D-COS). This research revealed clearly visible trends in NIR spectra related to the increasing hydrophilicity and the chemical nature of the polymer. It has been shown that changes in the NIR spectrum of water are also observed upon the interaction with very hydrophobic polymers (e.g., PTFE). Moreover, it was found that in the presence of different polymers, the revealed spectral patterns of water varied between the two main bands (νs + νas and νas + δ) in the NIR spectrum of water.