Chitin nanofibers are key components in several structural biological materials. Chitin nanofibers are often part of a hierarchical structure formed by chitin molecules assembled into larger nano- and microfibers, aligned, and assembled into a twisted plywood structure. As a result, structural biological materials often couple lightweight with exceptional mechanical properties. These biological materials are an inspiration for engineered biomimetic composites that incorporate chitin nanofibers. Here, we review engineering approaches to obtain chitin nanofibers and their applications.