Abstract: Under the strategic guidance of the "dual carbon" goals, carbon capture, utilization, and storage (CCUS) technologies have attracted widespread global attention, with carbon capture representing a critical step toward carbon neutrality. Conventional capture methods, such as chemical absorption, organic solvent adsorption, and membrane separation, are often hindered by severe equipment corrosion, high regeneration energy consumption, and low adsorption capacity, thereby necessitating the development of green and efficient alternatives. Porous liquids (PLs), first conceptualized in 2007, uniquely combine the permanent porosity of solid materials with the fluidity and processability of liquids, making them promising candidates for CO₂ capture. Among the four classical types of PLs, type III PLs—typically formed by dispersing porous host materials in steric solvents—have garnered significant attention due to their diverse material sources and facile preparation. Metal–organic frameworks (MOFs), characterized by well-defined pore architectures, high specific surface areas, and excellent designability, are ideal host materials for constructing type III PLs. This review systematically summarizes recent advances in MOF-based type III PLs, with a focus on preparation methods, structural characteristics, and CO₂ capture performance. Depending on the type of steric solvent used, four main categories are discussed: organic solvents, liquid polymers, deep eutectic solvents (DES), and ionic liquids (ILs). Organic solvent-based systems are easy to prepare but suffer from volatility and environmental concerns. Liquid polymers utilize size-exclusion effects to preserve MOF porosity, although they often lead to increased viscosity. DES-based PLs offer advantages in sustainability and tunability, with emerging applications in integrated CO₂ capture and conversion. ILs, owing to their negligible vapor pressure and structural tunability, are among the most extensively studied solvent systems, enabling stable dispersion and retention of MOF porosity. Strategies for enhancing system stability, including MOF surface engineering and the use of dispersion aids, are also highlighted. Furthermore, key characterization techniques are discussed, including structural analysis via X-ray diffraction and electron microscopy, measurements of physical properties such as viscosity and density, and stability evaluation. Given the limitations of conventional gas adsorption techniques for probing porosity in liquid media, positron annihilation lifetime spectroscopy (PALS) is introduced as an effective tool for verifying the permanent porosity of PLs. Preliminary techno-economic analysis indicates that material cost and cyclic stability remain the primary bottlenecks for large-scale application. Future research should therefore focus on (i) the rational design of low-cost, high-performance MOF-based porous liquid materials, (ii) the development of steric solvent systems with low viscosity and high CO₂ solubility, and (iii) the optimization of porous liquid systems under realistic flue gas conditions. Achieving these goals will facilitate the transition of MOF-based type III porous liquids from laboratory research to practical industrial applications.