The minimization of escalating atmospheric emission level of CO2 is alarming. Intensive research has been done to study the gas storage properties of the porous materials, especially, covalent organic polymers (COPs) and their functionalization to improve CO2 storage capacities. COPs are excellent for CO2 capture because of ultra-high specific surface area, high porosity, stability, and structural diversity. A background is reported on the CO2 sources, capturing strategies, separation technologies, the thermo-kinetic aspects of CO2 adsorption, and synthesis methods. This review provides an in-depth critical analysis of the current research on non-functionalized COPs and functionalized COPs with improved CO2 storage capacities. © 2020