This paper describes the development of a high-performance vitrified bonded cBN grinding wheel using a new type of ultrafine-crystalline cBN (cBN-U) abrasive grain. Surface plunge grinding experiments using a vitrified wheel made of the cBN-U grains with a mesh size of #80/100 were carried out, and the wheel’s grinding performance was compared with those of cBN vitrified wheels made of representative conventional monocrystalline and polycrystalline cBN abrasive grains. This new cBN-U abrasive grain was found to possess a higher fracture strength than these conventional cBN grains. Therefore, the cBN-U wheel exhibits a higher grinding ratio and longer grinding wheel life than conventional cBN wheels.