Tailoring　the　wavelength,　bandwidth,　directionality,　and　polarization　of　thermal　radiation　is　critical　for　various　applications　like　infrared　camouflage,　radiative　cooling,　and　gas　sensing.　In　this　work,　we　present　a　deep-subwavelength　bilayer　structure　that　serves　as　a　long-wavelength　infrared　(LWIR)　narrow-band　thermal　emitter　with　polarization　selectivity.　The　proposed　LWIR　thermal　emitter　basically　consists　of　a　tungsten　oxide　(WO3)　polar　dielectric　layer　upon　an　opaque　gold　(Au)　ground　plane.　Transfer　matrix　method　(TMM)　calculations　are　employed　to　analytically　investigate　the　optical　responses　of　the　thermal　emitter.　Leveraging　the　Berreman　mode　near　longitudinal　optical　(LO)　phonon　energy　of　WO3,　the　thermal　emitter　experimentally　realizes　high　absorption　(97.6%)　for　the　TM-polarized　state　and　low　absorption　(4.2%)　for　the　TE-polarized　state　(at　an　incident　angle　of　60°　and　a　wavelength　of　10.12　μm),　which　shows　good　agreement　with　theoretical　results.　Such　excellent　polarization-sensitive　performance　makes　our　LWIR　thermal　emitter　very　promising　for　optical　security　features,　information　encryption,　and　anticounterfeiting.　©　2025　American　Chemical　Society.