Abstract: Hydrogen cyanide (HCN) is a highly toxic compound, which poses significant adverse impacts on the environment and human health if it is discharged into the air without proper remediation. In this investigation, a novel collagen fibers-based aerogel was developed via freeze-drying method by utilizing collagen fibers (CFs) as raw materials with sodium carboxymethylcellulose (CMC) and polyethylenimine (PEI) serving as the binder and surface modifier for achieving the efficient adsorption and removal of HCN. CFs are featured with unique amphiphilicity, which enables the construction of supramolecular network structures through self-assembly. CMC and PEI worked as the binder to reinforce the as-formed three-dimensional network structure, while PEI also provides abundant alkaline amino functional groups to serve as adsorption sites to react with HCN, thus accomplishing efficient adsorption. The pore structure of the as-prepared aerogel was facilely regulated by changing the dosages of PEI, with a porosity as high as 92.56%. By applying the aerogel in the filtration of HCN-contained gas streams, the HCN reduction rate reached up to 50.55%, while the pressure drop was as low as 184.3 Pa.