<p>Cellulose-based aerogels, known for their low density and porous structure, require simple and eco-friendly methods to enhance their strength and adjust their structure. In this study, the interaction between cellulose nanofibers (CNFs) and layered double hydroxides (LDHs) was investigated via ion-exchange processes on both materials and their impact on aerogel performance. Counterion exchange (using H⁺, Na⁺, and Ca²⁺ ions) altered fibril interactions. Na⁺-exchanged CNFs exhibited the highest dispersibility and smallest pore size, followed by that of Ca²⁺ and H⁺. LDH dispersibility improved with Cl⁻ ions, and stable CNF–LDH hydrogel composites were formed. Aerogels comprising Na⁺ ions exhibited increased compressive strength with higher LDH content, whereas those comprising H⁺ exhibited a two-fold increase in strength at 20&#xa0;wt% LDH. Ca²⁺-exchanged aerogels initially had the highest strength but weakened with LDH owing to cross-linkage interference. Flame retardancy depended mainly on the LDH content and counterions, which influenced pore structure. Additionally, LDH incorporation significantly improved thermal insulation, reducing thermal conductivity to 0.026&#xa0;W/(m·K). With ultra-low densities (0.004–0.009&#xa0;g/cm³), these CNF–LDH aerogels show potential for advanced applications and further optimization.</p> Graphical abstract <p></p>