<p>Severe plastic deformation is well recognized for processing ultrafine-grained metals, and high-pressure torsion (HPT) is among the most effective techniques for achieving significant grain refinement at ambient temperature. By combining severe hydrostatic pressure with intense plastic shear straining, this study demonstrates the use of HPT for manufacturing fully dense bulk nanostructured metals directly from powder material. In this preliminary work, pre-alloyed CrMnFeCoNi high-entropy alloy (HEA) powders were processed via HPT. After 15 turns under 6 GPa at room temperature, the consolidated bulk sample reached 99.7% of the theoretical density, with a refined grain size of ~30&#xa0;nm across both the disk center and edge. Vickers microhardness exhibited a homogeneous distribution exceeding 500 <i>H</i>_V, and micromechanical properties were evaluated using nanoindentation. The measured mechanical properties and microstructural parameters were used to estimate the diffusion coefficient of the nanostructured HEA under plastic deformation during nanoindentation. Lattice defect evolution with increasing HPT turns was assessed by X-ray diffraction analysis. While the results are compared with earlier reports on cast CrMnFeCoNi HEA processed by HPT, particular emphasis is placed on the temperature increase during powder consolidation, which differs from bulk processing. This study demonstrates an HPT-based powder metallurgy route for producing nanostructured metals without external heating and advances understanding of plastic deformation in nanostructured CrMnFeCoNi HEA.</p>