A　facile　in-situ　ionothermal　synthesis　strategy　for　fabrication　of　ionic　liquids/metal−organic　frameworks　(MOFs)　(ILs@ZIF-8)　nanocomposites　hybrid　monolith　has　been　proposed　to　facilitate　highly　effective　capillary　microextraction　(CME)　of　ultra-trace　microcystins　(MCs)　in　environmental　waters.　The　ZnO　nanoparticles　(ZnO-NPs)　were　initially　introduced　into　a　precursor　polymer　monolith,　and　acted　as　the　metal　sources　and　anchoring　seeds　to　construct　ILs@ZIF-8　nanocomposites　hybrid　monolith　via　a　nanoparticle-directed　in-situ　growth　route　in　confined　imidazolium　ionic　liquids.　Detailed　characterization　based　on　scanning　electron　microscopy　(SEM),　X-ray　diffraction　(XRD)　and　N2　adsorption-desorption　isotherms　confirmed　that　both　the　morphology　and　porous　structure　of　ZIF-8　were　finely　tuned　by　the　incorporation　of　ILs,　which　acted　as　solvents　and　structure　directing　agent.　The　confinement　of　ILs　in　ZIF-8　framework　endows　the　ILs@ZIF-8　hybrid　monolith　additional　adsorption　sites　and　satisfied　water　stability　for　the　synergistic　enhancement　of　adsorption　efficiency　of　MCs　via　multiple　interactions　(including　π-π　stacking,　hydrogen　bonding,　hydrophobic　and　electrostatic　interactions).　Coupling　ILs@ZIF-8　hybrid　monolith-based　CME　to　LC-MS　enabled　an　efficient　and　sensitive　analysis　of　MCs　in　surface　waters　with　ultra-low　detection　limits　(LOD　≤　1.4　ng　L−1)　and　satisfactory　recoveries　(70.2%−107.0%).　This　study　showed　great　potential　for　feasible　design　and　fabrication　of　ILs@MOFs　composites　with　synergistic　and　tunable　structures　toward　efficient　sample　preparation　applications.　©　2023　Elsevier　B.V.