<p>Cellulosic aerogels and sponges, multifunctional materials, are typically fabricated from cellulose nanocrystals (CNCs) and nanofibrils (CNFs). The zero-dimensional (0D) structures of CNCs and one-dimensional (1D) structures of CNFs exhibit loose point-to-point and line-to-line interactions among their constituent building blocks. Consequently, fabricating functional and mechanically stable aerogels and sponges from these 0D and 1D building blocks typically requires chemical crosslinking—a process that complicates fabrication and adds to the structural mass. In contrast, cellulose acetate sponges constructed from nanofilms via cryo-templating exhibit high porosity (&gt;99%), low density (≤10 kg m⁻³), and a stable, continuous structure that does not require crosslinking while possessing mechanical properties comparable to those of crosslinked CNF sponges. These nanofilm-based sponges exhibit cell structures with a gradient thickness and increased apparent elasticity, which scales exponentially with relative density, characterized by a coefficient of 2.04 and an exponent of 2.48. Furthermore, they exhibit viscoelastic behavior, which is attributed to the bending of cell structures and the delamination and slippage of uncrosslinked nanofilms. This viscoelastic behavior can be altered by tailoring the pore size and pore distribution, thereby retarding stress relaxation and enhancing resilience.</p>