OBJECTIVE Two-dimensional hierarchically porous zeolitic imidazolate frameworks (H-ZIFs) show great promising applications in catalysis, gas separation, energy storage and sensing. Herein, a facile ionic-liquid-modulation approach is proposed for constructing H-ZIFs nanosheets with tunable thickness. METHODS Sulfo-functionalized zwitterionic ionic liquids (SFIL) have been designed as monodentate ligands to direct the formation of microporous nanosheets (ZIF-SFIL) in aqueous solution. Anions of SFIL have been tuned to modulate the coordination environment, enabling the control of the structure, thickness and pores of the nanosheets. RESULTS SFIL is demonstrated to pre-coordinate with Zn(II) to induce micropores with high specific surface areas (up to 1176 m2·g-1) and accelerate the nucleation of crystals. The BF4- anion serves as a competitive ligand to partially replace SFIL to cause structural defects, thus yielding hierarchically porous ZIF-SFIL nanosheets with high specific surface areas (270-466 m2·g-1) and variable thicknesses (from ca. 58 nm to ca. 455 nm). Benefiting from the versatile designability and multifunctionality of ionic liquids, the strategy in this work offers a facile approach for designing and constructing multifunctional materials with hierarchical pores.