The bulk-form in situ WC-based cermets were prepared by selective laser melting of W-C-Ni ternary powder system. The in situ formed WC crystals generally had a unique triangular microstructure which was developed via a layer-by-layer growth mechanism by the multilayered stacking of (0001) basal planes of WC. An increase in the applied laser energy density, which was realized by increasing laser power or decreasing scan speed, resulted in the coarsening of in situ WC crystals in both side length and thickness, due to the elevated heat accumulation at the tips of the triangular WC crystals.