<p>In this paper, the axial behavior of the concrete columns made of High-Performance Concrete (HPC) enhanced with Steel Slag as a Nano-material (NSS) subjected to elevated temperature has been experimentally investigated. The experimental program included testing of two groups of columns. The first has been made of conventional HPC in which silica fume and fly ash have been used as a partial replacement of cement, while the second group was produced using High-Performance Concrete with Nano Steel Slag (HPCNSS). Each group was tested under ambient and elevated temperatures, as well. A heating-cooling procedure has been adopted before applying the axial load test till the columns’ failure. The results include the failure mode, the load-deformation behavior, the secant stiffness, the failure load, and the toughness of the tested columns. The results showed significant enhancements in the failure load by 18.8% at ambient temperature and up to 49.1% at elevated temperature in some cases. For the secant stiffness, superior enhancement ranged between 48.1% at ambient temperature up to 57.8% at elevated temperature has been recorded. Furthermore, the minimum recorded enhancement in the columns’ toughness was more than 45.48% confirming the significant effect of adding NSS to the HPC. The present work focuses on full-scale column performance, providing new insights into their response to thermal loading.</p>