Para-aramid fiber was fibrillated in a dimethyl sulfoxide (DMSO)/tetrabutylammonium fluoride (TBAF) solution at 80 °C. Physical gelation of the dispersion liquid occurred by cooling to 20 °C at varying rates of 0.5 to 2.8 °C/min. The solvent was then replaced with acetone and the gel was dried by supercritical CO2 to obtain an aerogel. The fibril diameter decreased from ∼40 nm to 20 nm using a TBAF/DMSO ratio of 1:22 to 2:11, respectively. The specific surface area (SSA) of aerogel reached 702 m2/g at a fibril diameter of 20 nm. Prepared aerogel fiber with a diameter of 536 μm had a translucent appearance, an SSA of 473 m2/g, and a low density of 0.067 g/cm3. It bent freely and repeatedly without deformation or breaking.