It is extremely significant to address an urgency toward the development of low-cost and efficient catalysts. Herein, for the first time, we synthesize a novel self-assembled Ni/NiO@PANI by a combustible crystallization followed polymerization method, constructed by impregnation of Ni/NiO in sulfonic acid-doped polyaniline, which can be used as a bifunctional catalyst for electrochemical sensing of epinephrine (EP) and reduction of nitro- to amino-phenol (4-NP to 4-AP). Due to the unique nanoarchitecture, ferromagnetic feature of Ni, anti-corrosion feature of PANI, and synergy between the system (metal/metaloxide@carbon) leads superior performance: it can rapidly reduce the 4-NP pollutant to environmentally friendly 4-AP within 8 min, and easy magnetic recycling; Also, it can be used as a sensor for EP neurotransmitters with a sensitivity, detection, and quantification limit of 0.117 nAμM−1, 87.2, and 290.71 μM, respectively. This work provides a strategy to design low-cost and superior catalysts applied in catalysis and electrochemical sensor.