• Covalent organic framework nanofibers (CNFs) with biomimetic scale-like architecture, record-high aspect ratio (L/D = 103.05), and superior flexibility were directly synthesized via defect engineering.
• Self-standing membranes and nanofibrous aerogels (CNF-As) with designable micro-topological structures were fabricated with 100% CNFs.
• CNF-As perform photo-induced uranium extraction with an adsorption capacity and adsorption rate of 920.12 mg g−1 and 89.9%, respectively.
• CNF-As exhibit superior underwater stability (> 180 days) and superelasticity (~0% deformation after 500 compression cycles), making them promising for practical application in marine systems.