To shed light on the impact of severe deformation on the elemental segregation of high-entropy alloys (HEAs) as well as the related changes in mechanical properties, we systematically investigated the equiatomic CrMnFeCoNi HEA cold rolled and aging treated subsequently at 450 degrees C for varying time periods. Dislocation cells, nano-twins and shear bands of nanostructures form and significantly increase the strength of the as-cold-rolled HEA. Upon aging for 18-96 h, elemental segregation occurs in the dislocation cell and twinning regions. With the aid of higher strain localization, NiMn, FeCo and Cr-rich phases of nanoscale precipitate in the shear band regions. The elemental segregation slightly while the nanoprecipitations significantly increase the local hardness and the bulk strength. The nanoprecipitations also decrease the plasticity of the HEA due to the early cracking along the abundant interphase boundaries. These findings clarify the compositional changes and mechanical properties of the deformed HEAs upon aging, and also provide implications for the design and processing of advanced materials.