The new energy industry has increasingly higher requirements for the lightweight design and functional integration of the power energy system. As an effective solution to achieve this demand, a structural energy storage integrated composite was prepared that consists of a functional body with an ideal specific capacity combined with considerable mechanical properties. In this study, we prepared a CF@Mn₃O₄ composite by compounding polyacrylonitrile (PAN)-based carbon fiber (CF) with Mn₃O₄ through the three-step method of acid leaching activation, hydrothermal stirring, and high temperature annealing. As a result, the CF@Mn₃O₄ composite maintains a specific capacity of 610.5 mA h g⁻¹ after 150 cycles at the current density of 100 mA g⁻¹, which is approximately 2.48 times higher than that of the carbon fiber. The tensile strength, Young's modulus, and elongation of the CF@Mn₃O₄ composite reached 92.1%, 94.5%, and 93.5% of the original carbon fiber. These significant mechanical and electrochemical characteristics can be attributed to the synergistic effect of the carbon fiber substrate and Mn₃O₄. The carbon fiber served as a buffer substrate to relieve the volume expansion of the deposited layer during the charging and discharging processes, and the Mn₃O₄ was used as a coating layer to provide more insertion sites for lithium ions, which enables a higher charge–discharge specific capacity.