This work presents innovative strategies for engineering cellulose-based films with tailored functionalities, integrating physical structuring, chemical modification, and waste valorization to maximize resource efficiency. We introduce three key approaches: (1) Micropatterning via dewatering grids, enabling precise three-dimensional structuring of cellulose nanofibril (CNF) films. This method allows for tunable wettability, optical modulation, and enhanced tactile properties, with applications in water harvesting, coatings, and smart surfaces. (2) High-yield fibrillation of lignin-containing cellulose nanofibrils (LCNF), enhancing stability, UV shielding, and barrier performance, making them ideal for sustainable packaging solutions. (3) Hybrid CNF–lignin nanoparticle (LNP) composites, forming self-assembling surfaces with UV-blocking, antioxidant, and antimicrobial properties, offering superior food preservation compared to plastics. These strategies demonstrate the versatility of lignocellulose in designing high-performance, multifunctional materials. By tailoring morphology, chemistry, and structure, cellulose transitions from a passive substrate to an active component in sustainable packaging, energy-efficient construction, and circular technologies.