A therapeutic carrier in the second near‐infrared (NIR) window is created that features magnetic target, magnetic resonance imaging (MRI) diagnosis, and photothermal therapy functions through the manipulation of a magnet and NIR laser. A covellite‐based CuS in the form of rattle‐type Fe3O4@CuS nanoparticles is developed to conduct photoinduced hyperthermia at 808 and 1064 nm of the first and second NIR windows, respectively. The Fe3O4@CuS nanoparticles exhibit broad NIR absorption from 700 to 1300 nm. The in vitro photothermal results show that the laser intensity obtained using 808 nm irradiation required a twofold increase in its magnitude to achieve the same damage in cells as that obtained using 1064 nm irradiation. Because of the favorable magnetic property of Fe3O4, magnetically guided photothermal tumor ablation is performed for assessing both laser exposures. According to the results under the fixed laser intensity and irradiation spot, exposure to 1064 nm completely removed tumors showing no signs of relapse. On the other hand, 808 nm irradiation leads to effective inhibition of growth that remained nearly unchanged for up to 30 d, but the tumors are not completely eliminated. In addition, MRI is performed to monitor rattle‐type Fe3O4@CuS localization in the tumor following magnetic attraction. An effective, near‐infrared (NIR)‐responsive rattle‐type Fe3O4@CuS nanoparticle is developed to conduct magnetically guided photothermal tumor ablation and magnetic resonance imaging diagnosis through magnetic targeting. Based on the broad NIR absorption from 700 to 1300 nm, photothermal tumor ablation is evaluated by radiation at 808 and 1064 nm of the first and second NIR windows, respectively.