Intrinsic ferromagnetism at room temperature has been observed in ZnO/sapphire films by implantation of 200 keV Ni2+ ions with fluences 6×1015, 8×1015, 1×1016, and 2×1016 ions/cm2. Crystalline phases are identified by glancing angle x-ray diffraction, which shows no extra phase in the implanted films. Highest saturation magnetization (Ms) is observed in the film implanted with the fluence of 8×1015 ions/cm2 as examined by superconducting quantum interference device magnetometry. This film has almost 80% transmittance across visible wavelength range and hence a potential candidate of transparent ferromagnetic semiconductor. Defectlike oxygen vacancies in the films are studied by x-ray photoelectron spectroscopy. Ferromagnetism of the films is explained on the basis of bound magnetic polaron model.