Lightweight metal matrix composites have attracted a great attention for their technological application in aerospace, automotive, or sporting goods, and the multifunctionality of these composites will further expand the range of applications. Herein, a kind of lightweight 1–3 magnetostrictive FeCo/AlSi composites is investigated to evaluate the effects of the specific structure design and reverse magnetic field on the energy conversion under compression. The microstructure of the FeCo/AlSi composite before compression was observed, and the results indicate that there is a large bonding interface, which has the benefits of strain/stress transfer. Compared with the FeCo/AlSi composite with straight FeCo wire, a design with twisted FeCo wire significantly enhances the output performance of the magnetostrictive FeCo/AlSi composite. Furthermore, comparison of the output voltage for the FeCo/AlSi composite in the N–S mode (forward magnetization) and N–N mode (reverse magnetization) reveals that the reverse magnetization can improve the efficiency of the energy conversion notably. In addition, the results of the output voltage in the theoretical calculation are virtually consistent with that in practical measurement. Herein, a metal‐matrix lightweight FeCo‐based magnetostrictive energy harvester is proposed. A twisted structure design to improve the energy‐harvesting performance is used for the first time. A reverse magnetic field, differing from the traditional magnetization mode, significantly enhances the efficiency of energy conversion. A calculation model is established to predict the energy‐harvesting performance.