TiN nanoparticle-dispersed Si3N4 ceramics is one of the typical ceramics used for bearing applications. Because larger TiN particles considerably damage the mating metallic materials, smaller TiN particles must be dispersed in Si3N4 ceramics. In this study, we fabricated TiN nanoparticle-dispersed Si3N4 ceramics from Si3N4–nano TiO2 composite particles prepared by mechanical treatment. The mechanical properties of the fabricated TiN nanoparticle-dispersed Si3N4 ceramics were evaluated. At first, TiO2 nanoparticles were dispersed in ethanol using polyethylene imide as a dispersant with a lower molecular weight. Si3N4 powder was mixed with this slurry to obtain a powder mixture. In this case, the reaggregation of the TiO2 nanoparticles during the drying process is the problem that has to be solved. In this study, TiO2 nanoparticles and Si3N4 particles were mechanically joined by a particle composer to fabricate the composite particles from the powder mixture. TiN nanoparticles were uniformly dispersed in Si3N4 ceramics by using composite powder. The bending strength of the developed Si3N4 ceramics with TiN nanoparticles was improved, and its distribution was narrow due to the homogeneous dispersion of TiN nanoparticles.