The paper proposes a new ultra-high-precision machining technique, based on magnetic abrasive finishing, to achieve both high dimensional accuracy and surface accuracy of microscale-diameter materials that are difficult or impossible to machine conventionally. Microscale-diameter zirconia ceramic bars were used as the workpieces, and were machined by means of the proposed technique at different workpiece revolution speeds (1,000, 10,000, 20,000, and 35,000 rpm). Machining depth increased with workpiece revolution speed, and was the greatest for the highest speed studied of 35,000 rpm. The technique also yielded excellent performance in terms of the surface roughness; the initial surface roughness (Ra) of 0.18 µm was decreased to 0.02 µm under machining at 35,000 rpm for 40 s. SEM and AFM micrographs gave evidence of the technique’s high performance.