<p>Due to the significant public health concerns associated with SO₂ as a predominant pollutant, the SO₂ capture technologies are critically important. Ionic liquids (ILs) represent a promising class of solvents for SO₂ adsorption; however, their high viscosity and slow mass transfer characteristics hinder their practical application in SO₂ capture. This study focused on the immobilization of imidazole-based ILs, named [APMIM]Br and [BMIM]Br, onto activated carbon (AC) to develop solid ionic liquid absorbents (SILs) for the effective removal of SO₂ from simulated flue gas. The experimental results demonstrated that the first-order reaction rate constants for the SILs increased by approximately 3–6 times compared to the ILs alone. Additionally, the immobilization process significantly enhanced the adsorption capacities of the ILs in SILs. The calculated adsorption capacities for [APMIM]Br and [BMIM]Br in the SILs were 786.1&#xa0;mg/g and 418.0&#xa0;mg/g, respectively. It was observed that high temperatures had a detrimental effect on the adsorption process, while increased partial pressures of SO₂ substantially enhanced adsorption capacities. Furthermore, the presence of other gaseous components, such as CO₂, H₂O, and O₂, adversely affected the SO₂ removal efficiency of the SILs. The BMIM-AC exhibited excellent reversibility; in contrast, APMIM-AC demonstrated a reduction in adsorption capacity of approximately 22% after 5 cycles. The mechanisms of SO₂ removal by the SILs were believed to involve both a physical and chemical adsorption process. Given its outstanding cyclic adsorption–desorption performance, BMIM-AC is considered a promising alternative to the conventional SO₂ separation materials.</p>