In this study, the effect of nickel on the density and grain size of B₄C-TiB₂ nanocomposites produced by the pressureless sintering method was investigated. First, a B₄C-TiB₂ nanocomposite powder containing 10 wt% of TiB₂ nanoparticles was synthesized by chemical precipitation method and then different amounts of Ni (1.5 to 9.5 wt%) covered on the surface of these powders by electroless plating in a Ni-B electroless bath. The samples were sintered at 2100, 2175, and 2250 °C for 1.5 hours in the argon atmosphere. The results show that the addition of nickel to the B₄C-TiB₂ nanocomposites by using the electroless plating process has increased the sinterability of these materials. The highest density was obtained at 2100, 2175, and 2250 °C in 5.5 wt% of nickel, 82.22%, 98.26% and 98.44%, respectively. A sharp drop has occurred in relative density by increasing the amount of nickel to 7.5 and 9.5 wt%. The average grain size of the sintered samples increased at different temperatures by increasing temperature and increasing the amount of nickel.