For the purpose of assembling high-performance solid-state hybrid supercapacitors (HSCs) with superior cycling stability and energy density, biomass-derived multi-heteroatom-doped carbon materials were prepared in this work and utilized as negative electrodes for the supercapacitors. The applied biomass in this study included orange peel and egg white; besides, we also prepared Ag-doped egg white as a precursor through a denaturation reaction to synthesize a Ag-nanoparticle-decorated carbon material; the consequently obtained carbon materials were referred to as OC, EC, and Ag–EC, respectively. The as-synthesized heteroatom-doped carbon materials displayed excellent electrochemical performance. The specific capacitance retentions were 101.7, 105.4, and 107.4% for OC, EC, and Ag–EC, respectively, after 50 000 cycles. In addition, a core–shell structured C/N–CoO@CoO/NiO nanomaterial was also synthesized and used as the positive electrode, which exhibited a high cycling stability of 111.6% after cycling for 50 000 times. The three corresponding solid-state hybrid supercapacitors (HSCs) possessed excellent energy densities of 33.1, 30.1, and 35.6 Wh kg–1 at about 850.0 W kg–1, respectively. After cycling for 50 000 times, their specific capacitance retentions were 145.9, 139.2, and 140.0%, respectively.