The development of new CO₂ detection technologies and CO₂ “capture‐conversion” materials is of great significance due to the growing environmental crisis. Here, multifunctional triazine‐linked polymers with built‐in N‐heterocyclic carbene (NHC) sites (designated as NHC‐triazine@polymer) are presented for simultaneous CO₂ detection, capture, activation, and catalytic conversion. NHC‐triazine@polymer were readily obtained through polymerization of cyanophenyl‐substituted NHC. The obtained film‐like polymers exhibited interesting CO₂‐triggered fluorescence “turn‐on” response and CO₂‐sensitive reversible color change. Both NHC and triazine sites could act as efficient binding sites for CO₂, and the CO₂ uptake of NHC and triazine reached 1.52 and 1.36 mmol g⁻¹, respectively. Notably, after being captured by NHC, CO₂ was activated into a zwitterionic adduct NHC−CO₂ that could be easily transformed into cyclic carbonate in the presence of epoxides. Moreover, NHC‐triazine@polymer were stable and active catalysts for the conversion of low‐concentration CO₂ in a gas mixture (7 vol %) into cyclic carbonates as well as for hydrosilylation of CO₂ to formamides.