A　one-step　laser　lift-off　(LLO)　for　patterned　gallium　nitride　(GaN)　film　and　GaN-based　light-emitting　diode　(LED)　device　is　achieved　using　355　nm　picosecond　laser　irradiation　in　this　research.　The　laser　fluence　required　for　separation　is　0.09-0.13　J　cm(-2),　which　is　much　lower　than　that　for　the　currently　reported　LLO　methods.　The　separated　GaN　film　is　intact　with　only　0.04　GPa　of　residual　stress.　The　ultra-smooth　separated　surface　with　root　mean　square　roughness　of　only　5.2　nm　is　attributed　to　the　interconnection　of　microcrack-free　flat　cavities　formed　by　the　combination　of　high　photon　energy-induced　intrinsic　absorption　and　subsequent　plasma　generation.　The　flat　cavity　with　a　depth-to-width　ratio　of　1:4000　limits　the　delamination　region　to　a　few　nanometers　at　the　GaN/sapphire　interface.　GaN-based　LED　is　transferred　with　perfect　electroluminescence　(EL)　by　the　strategy.　The　stable　EL　spectral　peak　positions　and　intensity　independent　of　the　bending　state　prove　that　the　presented　low-energy　ultrafast　LLO　technique　ensured　the　flexibility　of　the　separated　LED　device　without　affecting　the　performance.　This　research　provides　a　promising　strategy　to　achieve　the　LLO　of　GaN　devices　with　low　energy　consumption,　high　controllability,　and　high　efficiency,　which　is　significant　for　the　industrial　fabrication　of　flexible　GaN-based　electronics.