Fiber membranes with unique functionalities has been developed to spur both academy and industry in filtration, clothing, and bio-medical fields. Now, many researches are aiming to fabricate multi-functional membranes for advanced applications. Bonding several functional membranes provides a facile way to fabricate a multi-functional membrane with high engineering and commercial values. The adhesives for bonding fiber membranes require both strong bonding characteristic and minimal effect on the structures and functionalities, because the functionalities of fiber membranes mainly comes from the base materials, coatings, porous structure, and dimensions, etc. Moreover, most commercialized adhesives with high bond strength and high water resistance are often derived from depleting petrochemical resources, which involves volatile organic compounds or other toxic compounds and causes environmental problems. In addition, as many functional membranes are used in biomedical applications, developing environmentally friendly and biocompatible adhesives are strongly required. Therefore, the development of natural and abundant source adhesives possessing excellent bonding characteristics is an industrial challenge and an important edge of the research field of adhesives. Here, we used chitosan as an adhesive for bonding several membranes into a multi-layered membrane. Chitosan is natural abundant bio-polymer obtained by alkaline deacetylation of chitin, abundant in crustaceans or insects. Chitosan is biocompatible as it has chemical structure of β-(1-4)-linked D-glucosamine and N-acetyl-D-glucosamine. Use of commercialized adhesives for bonding fiber membrane would result in loss of their original structure, porosity, and functionalities. However, novel chitosan bonding technique combined with vacuum filtration process enables to keep the structure, porosity, and functionalities of fiber membrane with minimal changes. In details, chitosan solution was applied on a fiber membrane and the membrane was filtered by aid of vacuum filtration, which lead to allocate chitosan on the interconnected area among the fibers. Post cross-linking process by using glutaraldehyde was applied to enhance the bonding strength and water resistance of adhesives. The tensile strength of adhesive was 0.7040 N/mm, which was about 4 times stronger than the tensile strength of a polypropylene membrane (0.1697 N/mm). Chitosan bonded multi-layer membrane retained their original flexibility and hydrophilicity. The novel chitosan bonding technique allows to fabricate multi-layer (up to 5 layers), multi-scale (fiber dia. From hundred nanometer to sub micron), multi-functional (air and water filter, drug delivery, antiadhesive) membrane. Due to its fast and facile bonding process, this technique will spur the development of multi-functional membranes.