Developing　hydrophobic　surfaces　for　flexible　fibrous　membranes　has　attracted　tremendous　attention　for　their　potential　applications　in　waterproofing,　antifouling,　and　drag　reduction.　However,　conventional　methods,　such　as　hydrothermal,　coating,　and　phase　separation,　often　involve　complex　preparation　processes,　plugging　of　porous　structures,　and　heavy　use　of　organic　solvents.　Herein,　a　facile　and　eco-friendly　assembly　strategy　is　proposed　for　fabricating　superior　hydrophobic　surfaces　on　fibrous　membranes.　Firstly,　a　hierarchical　rough　structure　was　created　on　the　fiber　surface　using　titanium　dioxide　nanoparticles　as　building　blocks　by　a　one-pot　procedure　based　on　electrostatic　complexation　and　interfacial　crosslinking.　The　procedure　is　performed　in　aqueous　media,　at　low　temperature　(50　degrees　C)　and　very　fast　(similar　to　20　min).　Subsequently,　a　waterborne　emulsion　was　developed　by　low-surface-energy　organosilicon　self-assembly　in　aqueous　media,　which　was　adopted　to　coat　fiber　substrate　for　surface　hydrophobization.　The　amount　of　organosilicon　is　reduced　by　＞90　%　of　that　required　in　the　traditional　coating.　Consequently,　the　resultant　fibrous　membranes　exhibit　a　robust　hydrophobic　surface　with　UV-resistant,　wash　durability,　photocatalytic　self-cleaning　effect,　and　excellent　breathable　properties.　Besides,　this　general　waterborne　hydrophobic　coating　strategy　could　be　applied　to　various　hydrophilic　substrates,　including　fabrics,　aerogels,　and　sponges.　This　work　provides　a　novel　method　to　design　and　fabricate　multi-functional　hydrophobic　surfaces.