Synthesis of a nanostructured pure phase nickel sulfide in a single step is a challenge. In this work, a new method for direct synthesis of uniform NiS–SiO2 submicrospheres was developed by ultrasonic spray pyrolysis. Colloidal silica was used as a sacrificial template to create the porous structure. After silica removal, hollow, porous pure phase NiS nanospheres were obtained. The product was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, transmission electron microscopy, and N2 adsorption/desorption isotherm. The results confirmed the formation of single phase millerite NiS porous nanospheres with a high surface area of 312 m2 g−1. The NiS spheres were tested as cathode for lithium batteries. A discharge capacity of 340 mAh g−1 with good capacity retention during multiple cycles was obtained.