Radon is a colorless and radioactive noble gas, which can severely harm human health during acute exposure. So, it is highly necessary to improve ways of capturing Rn gas for the purpose of radiation protection. In this work, the approach of density functional theory, was employed to study 222Rn capture capacity of functionalized h-BN. Various functional groups such as COOH, PO4 and NH2 were tested on h-BN to 222Rn capture. At normal temperature and pressures, the adsorption energies of 222Rn atoms captured on COOH, PO4 and NH2 functionalized h-BN were − 7.41, −115.72 and − 10.75 eV respectively. We observed significant changes in the structural properties of the systems after adsorbing 222Rn atoms. For example, COOH functionalized h-BN adsorbed radon by the nearest B, N atoms having a contracted bond length of 1.42 Å, which is 0.02 Å less than the optimized system before taking radon. Increase in temperature under ambient pressure led to several changes in the value of adsorption energy, which revealed 1000 K as the most favourable temperature for 222Rn capture. Calculation results showed that the obtained negative entropy was due to physisorption of 222Rn, while positive entropy was attributed to chemisorption of 222Rn. In this work, we anticipated PO4 functionalized h-BN as the best performing system due higher polarity and dipole interactions. Finally, the active performance of these functional groups to enhance 222Rn capture promotes sustainability of this work because it will help reduce cost of production by using environmentally friendly materials such as N, P and C.