Volatile organic compounds (VOCs) are toxic chemicals, detrimental to humans and the environment. Currently, there is no fully satisfactory method for VOC removal from indoor air. Formaldehyde, a well-known and ubiquitously present VOC, should be removed because of its various adverse effects on human health. In this study, we developed a method for removal of formaldehyde using porous enzyme/chitosan nanofibre composites. To identify the gene for a formaldehyde-degrading enzyme, we examined the involvement of the alcohol dehydrogenase gene (alcA) of Aspergillus oryzae in formaldehyde degradation. Using an alcA-disrupted strain, we found that formaldehyde degradation was lower in this mutant strain than in the control strain, suggesting that this enzyme played an essential role in formaldehyde degradation. Next, we assessed the ability of the crude enzyme extracted from A. oryzae to degrade formaldehyde in vitro. The enzyme showed a formaldehyde degradation rate of 50 ppm in 30 h. We then produced porous enzyme/chitosan nanofibre composites by mixing the crude enzyme and a 10% (w/v) chitosan nanofibre suspension, followed by freeze-drying. Characterization of the enzyme/chitosan nanofibre composites was carried out by X-ray photoelectron spectroscopy. Formaldehyde degradation tests were carried out using porous chitosan nanofibre and porous enzyme/chitosan nanofibre composites. Based on this analysis, we found that the porous enzyme/chitosan nanofibre composites showed a greater formaldehyde degradation ability than that of the porous chitosan nanofibres. When using the porous enzyme/chitosan nanofibre composites, formaldehyde was efficiently removed via enzymatic degradation and chemical adsorption by chitosan. These findings suggested that porous enzyme/chitosan nanofibre composites have a high capacity for the degradation of formaldehyde in the vapour phase.