<p>To address the challenge of carbon dioxide accumulation in confined environments, a poly(vinyl alcohol) (PVA)-based, organic–inorganic hybrid hydrogel system was developed for CO₂ capture via mineralization. A PVA-based hydrogel functionalized with tetraethyl orthosilicate (TEOS) and impregnated with CaCl₂ was fabricated for efficient CO₂ capture under humid indoor conditions. The hydrogel exhibited tunable porosity, high elasticity, and mechanical integrity, attributed to the synergistic effects of physical freeze–thaw crosslinking and TEOS-mediated covalent bonding. The presence of Ca ions within the hydrogel enabled effective CO₂ mineralization under humid conditions, leading to the formation of CaCO₃ polymorphs, as confirmed by SEM, XRD, and FT-IR analyses. Thermogravimetric analysis demonstrated that the hydrogel could accommodate over 35 wt% CaCO₃, indicating its substantial CO₂ uptake capacity of more than 15 wt%. This strategy demonstrates the potential of PVA-based hybrid hydrogels as functional platforms for carbon dioxide capture in confined spaces, combining physical robustness with ion-mediated CO₃ sequestration<b>.</b></p> Graphic abstract <p>Ca ion-functionalized PVA-based hydrogel that was hybridized with silica was newly developed for the effective capture of CO₂ in humid indoor environments. CO₂ capture was successfully accomplished via mineralization of CO₂ to CaCO₃ in the hydrogel.</p> <p></p>