• Novel cyclotriphosphazene-based PMO-CPFs with tunable porosity are developed. • The PMO-CPFs show exciting dual-functions for CO 2 adsorption and conversion. • The PMO-CPF-catalyzed coupling reaction can perform under mild and green conditions. • The catalyst is easily separated and shows good structural stability and reusability. The design and development of advanced functional materials for efficient absorption and selective conversion of carbon dioxide (CO 2 ) remains a challenging research topic. In this work, novel cyclotriphosphazene-based periodic mesoporous organosilicas (PMO-CPF) with various contents of active components and tunable porosity were successfully prepared via direct co-condensation method, and their structures were characterized by FT-IR, solid-state 13 C, 29 Si and 31 P NMR, XRD, N 2 adsorption–desorption, HR-TEM and TGA techniques. The PMO-CPFs as-prepared were applied for CO 2 adsorption and conversion into cyclic carbonates, and the adsorption capacity and catalytic behaviors were thoroughly investigated. The PMO-CPFs integrate the structural features of high specific surface area, Lewis basic units and multiple dual hydrogen bond donor (HBD) groups, which endow the materials with dual functions of CO 2 adsorption and epoxide activation by forming dual hydrogen bonds. The optimum PMO-CPF-20 combining with tetrabutylammonium iodide (TBAI) showed an excellent activity for the cycloaddition of CO 2 to propylene oxide (PO), and could afford 98% propylene carbonate (PC) yield with above 99% selectivity under the conditions of 90 °C and 2.0 MPa for 6.0 h. Moreover, the catalyst reusability and applicability to epoxides with different substituents were studied, and a feasible catalytic mechanism was finally proposed. The developed metal-free, robust and bifunctional mesoporous organosilicas here were suggested to be advanced materials for CO 2 adsorption and subsequent catalytic conversion.