Functionalized covalent triazine frameworks (CTFs) realized by rational design of the monomer have been recognized as a promising candidate to achieve improvements in various applications. Here, new CTFs, 1,3-bis(pyridyl) imidazolium-based CTFs (bpim-CTFs), have been prepared via incorporation of an imidazolium motif into the monomer, which resulted in high functionalization of the frameworks. The bpim-CTFs showed N-rich environments, excellent micro-porosity (up to 1550 m² g⁻¹) and high thermal stabilities, promising for efficient CO₂ capture. The bpim-CTF-500 showed the highest CO₂ uptake capacity of up to 2.77 mmol at 1 bar at a temperature of 298 K, which is higher than those of most of the other POFs except a few examples. Additionally, the frameworks featured moderate CO₂ selectivity over N₂ up to 32.