In recent years, ionic liquids (ILs) possessing attractive physicochemical properties including negligible vapor pressure, outstanding thermal and chemical stability, good ionic conductivity, nonflammability, nontoxicity, etc., have been widely used in inorganic synthesis as template, all-in-one medium, and materials precursor. In this chapter, we discuss the roles and advantages of ILs in shape control for inorganic materials, and propose the effects of the ILs as being guided by the principles of geometric matching and adsorption configuration. We summarize many of the most recent advances in the IL-assisted synthesis of nanomaterials from zero-dimensional, one-dimensional, two-dimensional to three-dimensional structures, along with the corresponding synthetic processes and structure formation mechanisms. This chapter also highlights some limitations of the ILs that should be addressed in furtherance of wider practical applications.