Mg B 2 ∕ Fe tapes with 2.5–15at.% ZrB2 additions were prepared through the in situ powder-in-tube method. The phases, microstructures, critical current density, and flux pinning were characterized by means of x-ray diffraction, scanning electron microscope, and magnetic and transport property measurements. Compared to the pure tape, a significant improvement in the in-field JC was observed for all the ZrB2 doped samples, while the critical temperature decreased slightly. The highest JC value was achieved for the 10at.% doped sample. At 4.2K, the transport JC increased by more than an order of magnitude than the undoped one in magnetic fields above 9T. Nanoscale segregates or defects caused by the ZrB2 additions which act as effective flux pinning centers are proposed to be the main reasons for the improved JC field performance.