Metal matrix nanocomposites (MMNCs) are anticipated to offer significantly better performance than existing superalloys for additive manufacturing (AM). However, traditional methods of preparing MMNC powder, such as high-energy ball milling, usually involve high cost and high energy consumption. This paper reports experimental results on a novel method to prepare MMNC feedstock powder. Nickel/alumina MMNC powder was successfully produced using electroless plating, containing a high fraction (66 vol. %) of alumina nanoparticles. Then, the MMNC powder was compacted into a disk shape with a hydraulic press and sintered with a tube furnace. After sintering at 1400 C for 4 hours, the MMNC had a density of 4.16 g/cm3. Scanning electron microscopy observation, and X-ray diffractometry and energy-dispersive X-ray spectroscopy analysis were conducted on the sintered Ni/Al2O3 disk. As the alumina nanoparticles were added to nickel, an increased microhardness of HV0.5 189 was obtained.