A method of controlling vibration and harvesting energy for whole spacecraft is proposed by designing a device integrating lever-type nonlinear energy sink (LNES) and giant magnetostrictive material (GMM), which is installed in a whole-spacecraft system model. The amplitude and voltage data of the whole-spacecraft structure under sine sweeping excitation are captured using Simcenter Testlab (LMS) software and an oscilloscope. The experimental model is modeled as a two-degree-of-freedom main system with a nonlinear system. The magnetostrictive effect of the GMM is examined using the Jiles–Atherton model. The experimental results (that is, the transmissibilities, formant frequencies, and voltages) confirm that this device can achieve efficient vibration control and harvesting energy under different working conditions. Moreover, appropriate parameter selection can enhance its performance, which is consistent with our theoretical analysis. In summary, the theoretical and experimental results suggest that a LNES–GMM device can reduce amplitude and generate electrical energy without significantly changing the natural frequency of the whole-spacecraft system.