Optical　controlling　of　solid-sate　electric　properties　is　emerging　as　a　non-contact　and　nondestructive　avenue　to　optimize　the　physical　properties　of　electronic　and　optoelectronic　devices.　In　term　of　strong　light-material　coupling,　two-dimensional　(2D)　double　perovskites　hold　great　prospects　to　create　photo-dielectric　activities　for　high-performance　device　applications.　Here,　we　have　achieved　the　photo-excited　switching　and　enhancement　of　dielectric　properties　in　the　orientational　thin　films　of　a　2D　double　perovskite,　(C4H12N)4AgBiI8　(1,　where　C4H9NH3+　is　isobutylammonium).　It　undergoes　a　structural　phase　transition　at　384　K　(Tc),　triggered　by　the　dynamic　ordering　of　organic　cations　and　tilting　motion　of　isometallic　perovskite　sheets.　Most　notably,　the　orientational　thin　films　of　1　are　extremely　sensitive　to　light　illumination,　of　which　the　dielectric　constants　can　be　facilely　photo-switched　between　the　low-　and　high-states.　During　this　photo-switching　process,　the　dielectric　constants　are　enhanced　with　a　magnitude　up　to　~350%　under　405　nm,　far　beyond　most　of　the　inorganic　phase　transition　counterparts.　In　addition,　this　photo-excited　switching　and　enhancement　of　dielectric　response　exhibits　an　operational　stability　with　superior　anti-fatigue　characteristics.　Our　work　opens　up　a　potential　avenue　for　assembling　high-performance　optoelectronic　devices　with　the　controllable　physical　properties.　©　2024　SIOC,　CAS,　Shanghai,　&　WILEY-VCH　GmbH.