Photoacoustic　imaging　(PAI)　has　evolved　to　a　stage　that　high-performance　exogeneous　contrast　agents　are　urgently　needed　for　imminent　biomedical　and　clinical　applications.　Given　that　a　material　meets　the　basic　criteria　of　efficient　photoacoustic　conversion,　high　biocompatibility,　and　fast　excretion,　great　effort　has　been　devoted　to　evaluating　various　materials　for　developing　advantageous　contrast　agents　to　explore　the　full　potentials　of　PAI.　One　focus　is　through　modification　of　the　current　agents　to　boost　their　PA　performance;　whilst　the　other　focus　is　to　develop　novel　agents.　Antimonene　(AM)　has　emerged　as　a　promising　candidate　for　next　generation　of　electronics　among　2D　materials　due　to　its　outstanding　properties.　Herein,　it　is　reported　that　liquid-phase　exfoliated　antimonene　exhibits　extraordinary　photoacoustic　performance,　which　is　not　only　more　advantageous　than　other　2D　materials,　such　as　black　phosphorus,　graphene　oxide,　and　transition　metal　dichalcogenides,　but　also　superior　to　the　commonly　used　PA　contrast　agents,　such　as　ICG　and　gold　nanorods.　An　insight　analysis　reveals　that　the　unique　thermal　property　of　AM,　including　intrinsic　low　thermal　conductivity　and　the　morphology-related　high　interfacial　thermal　conductivity,　might　interpret　the　high　photothermal　conversion　efficiency,　and　thus　the　excellent　photoacoustic　performance.　The　prodigious　performance　allows　sensitive　monitoring　of　intracellular　events　and　high-quality　in　vivo　tumor　imaging.