Hemp (Cannabis sativa L.) seeds contain a high concentration of proteins and biologically active compounds. The protein content is even higher in case of lipid part removal in oil production. The remaining part is considered a leftover, usually being used in animal feed. The aim of this study was to investigate the physicochemical composition of hemp seed cake flour, its nutritional quality and its impact on bread quality parameters. The properties of hemp seed cake flour were assessed in terms of protein quality, mineral composition, polyphenols and antioxidant activity. Hemp seed cake proved to be an important source of high-quality protein (31.62% d.m.) with the presence of eight essential amino acids. The biologically active potential of hemp seed cake has been demonstrated by the high content of polyphenols, especially those from the Cannabisin group. Hemp seed cake flour was incorporated in wheat flour at levels from 5 to 40% (w/w) to investigate its influence on bread quality parameters. The addition of hemp seed cake flour increased the total phenol content of bread, thus greatly enhancing the antioxidant activity. The protein content of bread was found to be enhanced from 11.11% d.m (control sample) to 18.18% d.m (for sample with 40% hemp seed cake flour). On the other hand, the addition of hemp seed cake flour led to decreased bread porosity, increased hardness and decreased resilience in the seed cake. Although, all bread samples recorded sensorial attributes ranging between “slightly like” and “like it very much”.