Radiation-induced single event upsets (SEUs), or soft errors, have become a dominant factor in the reliability degradation of nanoscale memories. In this paper, based on the SEU physics mechanism, and reasonable layout-topology, a novel soft error hardened memory cell is proposed in 65 nm Complementary Metal Oxide Semiconductor (CMOS) technology. The design comparisons for several hardened memory cells in terms of access time (read access time and write access time), power consumption, and layout area are also executed. The main advantage of the proposed cell is that it can provide 100% fault tolerance, which is very useful for memory applications in severe radiation environments. Furthermore, Monte Carlo simulations are carried out to evaluate the effects of process, voltage, and temperature (PVT) variations. From simulations, we confirmed that the proposed cell has exhibited a sufficient multiple-node upset tolerance capability even under PVT variations.