Ionis liquids (ILs) are promising novel thermodynamic gas hydrate inhibitors (THIs) that have gained an ongoing experimental and modeling research prospect over a decade. In view of this, the path to developing desirable ionic liquids THIs depends on understanding the state-of-the-art methods of ILs hydrate inhibition impacts and factors that influence their performance. This review provides a holistic summary of the use of ILs as THIs. Almost all the available thermodynamic hydrate inhibition data of different gas systems in the presence of ILs at varying concentrations were critically reviewed and analyzed. Also, all ILs hydrate-related phase behavior modeling studies and their prediction accuracies are discussed in this work. The hydrate phase boundary inhibition effects of each IL are provided alongside factors that affect their inhibition performance. The study showed that IL cations, anions, and chain length characteristics control their hydrate inhibition impacts. By far, a narrow hydrate suppression temperature window below 3 K at 10 wt IL concentration has been achieved with accurate predictions using various models. This narrow THI performance window could be enhanced by exploring novel IL families with low molecular weights, well-optimized cation-anion interactions, and active hydrogen bonding interactive functionalities. The findings presented in this work are relevant for future IL-related breakthrough research in hydrate inhibition technologies. ©