Ionic liquids (ILs), as a novel class of molecular platforms with structural tunability, play a significant role in the construction of functional composite materials. Their structural designability enables them to function not only as conventional solvents but also as synthetic media, pore modifiers, functional components, and structure-directing agents. The combination of ILs with reticular materials generates functionalized systems with synergistic effects. The introduction of ILs can modulate the pore architecture, chemical microenvironment, and stacking modes of reticular materials, endowing them with superior performance in catalysis, separation, and energy-related applications that surpass those of single-component materials. This review systematically summarizes the research progress on the application of ILs in reticular materials. First, the synthetic strategies and structure-regulation principles of IL/reticular material composites are analyzed. Second, the multifunctional roles of ILs in the synthesis of reticular materials—as solvents, templates, and structure-directing agents—are summarized. Subsequently, their application progress in CO₂ capture and conversion, catalysis, separation, and energy-related fields is systematically introduced. Finally, the challenges and future directions in this field are discussed. This review aims to provide a systematic theoretical reference for researchers working on porous materials, ionic liquids, and functional composites.