Alkaline-activated materials and geopolymers are materials derived from the alkaline activation of aluminosilicate precursors. Their production is based on the reaction of raw materials rich in silica (SiO₂) and aluminum (Al₂O₃) with alkaline activators. They have been known for many years and are regarded as a viable alternative to traditional binders. One crucial aspect of these materials is their potential to capture and permanently immobilize CO₂ molecules within their structure, owing to their chemical composition and inherent porosity. This feature can bring significant environmental benefits and contribute to reducing atmospheric CO₂ levels, especially in the context of large-scale industrial use. Alkali-activated materials rank among the most promising systems for CO₂ reduction and may form a crucial component of future strategies aimed at combating climate change. At least three main mechanisms of CO₂ sequestration in such materials have been identified, including physical and chemical adsorption, as well as carbonate formation. However, this topic still faces substantial challenges that need to be addressed by the scientific community. This paper presents the current state of knowledge regarding CO₂ sequestration mechanisms in geopolymer and alkali-activated materials, while also outlining key future directions and research priorities.