Polysulfone (Psf) is the most commonly used polymer for the ultrafiltration membrane applications. Though it is regarded as high-performance engineering thermoplastic, it has γ-radiation stability only up to 100 kGy. When exposed to γ-radiation, the polymeric chains undergo scission and cross-linking, leading to a change in the cross-linking density and degradation in membrane performance. For the first time, carboxylated nanodiamonds (CND) are incorporated into Psf matrix in order to enhance the radiation resistant property of the membranes. Psf-CND composite membranes were fabricated with different loadings of CND (0.1–1 wt%) and exposed to different doses of γ-radiation up to 1000 kGy. The nanomaterials and (un) irradiated membranes were characterised using different instrumental techniques like FESEM, TEM, XPS, DSA, UTM, and DSC. It is claimed that CND helps in homogeneous dispersion of nanoparticles in the membrane matrix while protecting it from the radiation environment by scavenging of radiolysed products of water. The membrane with an optimum loading of 0.5% CND was found to be stable up to 1000 kGy of radiation dose which is 10 times as compared to that of control Psf membrane. The present study has significantly opened up opportunities for enhancing the deployment of polymeric membranes in radioactive effluent treatment. © 2019 Elsevier B.V.