Iron oxide nanoparticles (IONPs) for magnetic hyperthermia in cancer treatment have recently gained substantial interest. Unfortunately, the use of free IONPs still faces major challenges such as poor tumor targetability, high variability in the amount of IONPs taken up by the tumor and the IONP leakage from dead cancer cells into the surrounding healthy tissues. The present work reports on electrospun fiber webs, heavily loaded with 50 nm sized IONPs. The high loading capacity of the fibers enables significant heating of the environment upon applying an alternating magnetic field. Furthermore, magnetic fibers can be repeatedly heated without loss of heating capacity or release of IONPs. Upon functionalization of the fiber surface with collagen, human SKOV-3 ovarian cancer cells attached well to the fibers. Applying an alternating magnetic field during 10 minutes to the fiber webs killed all fiber-associated cancer cells. Killing the cells using this method seemed more efficient compared to the use of a warm water bath. As the fiber webs can be i) loaded with a well-controlled amount of IONPs and ii) localized in the body by Magnetic Resonance Imaging, magnetic electrospun fibers may become promising materials for a highly reproducible (repeated) heating of cancer tissues in vivo.