Carbon　aerogels　have　demonstrated　superior　properties　for　generating　clean　water　through　sustainable　solar　steam　generation.　However,　the　complex,　time-consuming　preparation　process　and　the　various　harmful　chemicals　involved　seriously　inhibit　the　development　and　applications　of　carbon　aerogels.　Herein,　down　biomass-based　carbon　fiber　aerogel　(DCFA)　consisting　of　physically　self-interlocked　carbon　fibers　was　developed　through　the　simple　low-temperature　carbonization　of　natural　down　cluster　(DC)　for　highly　effective　solar　evaporation.　The　resulting　DCFA　has　a　large　amount　of　carbon　(＞80　%)　and　small　amounts　of　sulfur　and　nitrogen　due　to　its　natural　disulfide　bonds　and　amino　groups,　suggesting　a　unique　self-doped　carbon　property.　The　low　density　and　high　porosity　of　the　DCFA　increased　the　total　solar　absorbance　and　suppressed　the　energy　loss　during　evaporation.　As　a　result,　the　DCFA　possessed　solar　absorbance　of　97.03　%,　as　well　as　high　evaporation　rates　of　2.05　and　2.11　kg·m−2·h−1　for　the　treatment　of　saline　water　and　dye　water,　respectively,　which　are　higher　than　most　reported　results.　Moreover,　the　resulting　DCFA　could　self-float　without　external　assistance,　demonstrating　that　it　could　be　a　facile　evaporator　in　practical　applications.　Additionally,　the　DCFA　retained　its　evaporation　performance　after　10　times　tests　for　the　evaporation　of　3.5　wt%　saline　water　and　actual　dye　wastewater,　indicating　a　long-term　capacity　for　practical　employment.　These　findings　suggest　that　the　DCFA　could　be　a　feasible　alternative　for　solar-driven　evaporation.　Simultaneously,　the　simple,　efficient,　and　chemical-free　strategy　will　inspire　subsequent　research　on　the　construction　of　fiber-based　functional　aerogels　and　their　further　development/application　in　water　treatment,　thermal　insulation,　energy　generation,　energy　storage,　and　other　related　areas.　©　2023　Elsevier　B.V.