Supercapacitors (SCs) based on representative electrochemical electrode materials were assembled and artificial seawater has been proposed as an electrolyte for application in supercapacitor devices for the first time. Seawater is an eco-friendly and unlimited resource and its use as an electrolyte is an entirely new concept for SCs systems. Partially graphitized N-doped porous carbon, MnO2/polypyrrole composite, and Fe2O3 nanosheets were prepared to investigate the electrocapacitive properties of active materials in artificial seawater electrolyte. Furthermore, the aforementioned electrode materials were utilized to fabricate SC devices as the artificial seawater-based supercapacitors. More importantly, long-term cycling tests revealed that carbon-based SC devices showed much higher cycling stability than the other types of SC devices with the former having a high potential for practical application.