Increasing　upconversion　luminescence　(UCL)　to　overcome　the　intrinsically　low　conversion　efficiency　of　upconversion　nanoparticles　(UCNPs)　poses　a　fundamental　challenge.　Photonic　nanostructures　are　the　efficient　approaches　for　UCL　enhancement　by　tailoring　the　local　electromagnetic　fields.　Unfortunately,　such　nanostructures　are　sensitive　to　environmental　conditions,　and　the　regulation　strength　is　varied　in　flexible　applications.　Here,　we　report　giant　UCL　enhancement　from　a　flexible　UCNP-embedded　film　coupled　with　a　microsphere　photonic　superlens　(MPS),　by　which　the　enhancement　ratio　of　UCL　is　over　10(4)-fold　under　808　nm　excitation　down　to　0.72　mW.　The　enhancement　pathways　of　MPS-enhanced　UCL　are　attributed　to　Mie-resonant　nanofocusing　for　high　excitation-photon　density,　optical　whispering-gallery　modes　(WGMs)　for　fast　radiative　decay,　and　the　directional　antenna　effect　for　far-field　emission　confinement.　The　contribution　of　optical　resonance　in　the　MPS　to　suppressing　the　phonon-induced　nonradiative　transition　and　thermal　quenching　is　experimentally　validated.　The　UCL　quantum　yield　is　therefore　improved　by　3-fold　to　4.20%　under　120　mW/cm(2)　near-infrared　excitation,　consistent　with　the　enhancement　ratio　via　the　Purcell　effect　of　WGMs.　Furthermore,　the　MPS　demonstrates　the　robust　optical　regulation　capability　toward　flexible　applications,　opening　up　new　opportunities　for　facilitating　multiphoton　upconversion　in　wearable　optoelectrical　devices　for　nanoimaging,　biosensing,　and　energy　conversion　in　the　future.