Porous liquids (PLs), an emerging porous material with permanent cavities, have attracted extensive attention in recent years. However, the current construction methods are complicated and resulting PLs possess high viscosity values, which cannot meet the requirements of practical industrial applications. Herein, we demonstrate a generalizable and simple strategy to prepare type III PLs with low viscosity based on the rule of “like dissolves like”. Specifically, the monoglycidyl ether terminated polydimethylsiloxane (denoted by E-PDMS) is attached to the surface of Universitetet i Oslo (UiO)-66-NH₂ via covalent linkage, constructing the pore generator (UiO-66-NH₂-E-PDMS, denoted by P-UiO-66). Then, P-UiO-66 is dispersed into different types and amounts of sterically hindered solvents (PDMS400 or PDMS6000), obtaining a series of type III PLs (denoted by P-UiO-66-PLs) with permanent cavities and low viscosities. The gas sorption–desorption test shows that P-UiO-66-PLs have an enormous potential for CO₂/N₂ selective separation. Besides, the porosity of P-UiO-66-PLs and the CO₂ sorption mechanism are demonstrated by molecular simulation. Furthermore, the generality of the synthesis strategy is confirmed by the successful construction of PLs using two other amino-metal-organic frameworks (MOFs) (MIL-53(Al)-NH₂ and MIL-88B(Fe)-NH₂). Importantly, it’s worth noting that the strategy based on the rule of “like dissolves like” sheds light on the preparation of other types of PLs for task-specific applications.