At this time, multi-application materials are developing to match the trend of green sustainable energy development. And with characteristics acting as high porosity, light weight, bulk form with diverse pores, and high chemical compatibility, metal-doped carbon aerogel becomes a potential material. In this study, Fe-doped carbon aerogel with crosslinking sodium alginate (Fe-SA-CA) was synthesized through a simple process of freeze-drying, aerogel pyrolysis, and pyrolysis temperatures (600–800 °C) were investigated to find suitable materials for adsorption and electrochemical applications. The characteristics of the material are analyzed by modern methods, proving that the surface of the material has a variety of pores with a size approximately 2 nm, and has the main components including C, O, and Fe. Fe-SA-CA shows potential for adsorption of oils, organic solvents, and crystal violet pigments. In particular, electrochemical properties of Fe-SA-CA are determined through cyclic voltammetry, galvanostatic charge discharge, and electrochemical impedence spectroscopy, to obtain high specific capacitance (203 F/g at 50 mV/s), constant discharge capacity over 500 cycles. Futhermore, thanks to the presence of the element Fe, the magnetic material is easily recovered with a magnet after used. In addition, the precursor used in the study is cellulose from nipa coconut shells - a large amount of biomass waste in Vietnam, thereby reducing production costs, limiting chemicals, and expanding the potential application of the Fe-doped carbon aerogel.