Infrared (IR) nanospectroscopy, with a lateral resolution of 20 nm, has been utilized to investigate the chemical composition of wood cell walls, bleached pulp, cellulose nanofibrils (CNF filaments), films and wood-based aerogels. This high-resolution technique enables the acquisition of detailed infrared spectra and spatially resolved chemical maps, allowing precise characterization of cell wall layers, some only a few hundred nanometres wide. By examining different regions of the cell wall—such as the primary wall, secondary wall layers (S1, S2, S3), and cell corners—this approach provides insights into the structural organization and spatial variations of cellulose, hemicellulose, and lignin. To capture both large-scale and nanoscale details, infrared images are taken over areas (20 × 20 µm) and (3 × 3 µm) to study heterogeneous structures. In addition to wood cell walls, CNF filaments were analysed under different drying conditions to observe structural and chemical changes. CNF films prepared using different techniques were investigated. Bleached pulp was also investigated to observe presence of cellulose.  Furthermore, wood-based aerogels were examined after NaOH treatment to understand modifications in their chemical composition. These findings contribute to the development of bio-based materials and environmentally friendly processing techniques, enhancing the understanding of wood-derived materials for sustainable applications.