We present a photoluminescence study of InP nanostructures monolithically integrated to Si (100) substrate. The InP nanostructures were grown in pre-formed pits in the silicon substrate using an original approach by metal–organic vapor phase epitaxy via selective area growth driven by molten alloy. The obtained InP/Si nanostructures have submicron size above and below substrate surface. InP nanostructures were investigated by photoluminescence spectroscopy at temperatures in the range of 5–300 K and at different pump power. Room temperature photoluminescence spectra of the studied structures exhibit the peak corresponding to zinc blende InP band gap. The obtained results show high crystalline quality of the InP material.