The effect of electronegative substituents on the diamond nucleation on hexagonal boron nitride (h-BN) was investigated theoretically by using the DFT method. Fluorine and hydroxyl were used as substituents on zigzag edge atoms of the basal plane. Outgrowths corresponding to diamond nuclei were calculated to be energetically more stable than the corresponding growth of graphite nuclei for both types of substituents. A comparison between the nucleation of diamond on H-terminated and substituted h-BN edges showed only small energy differences. The effect of the larger electronegativities and radii of F and OH on the stabilization energy of the diamond nucleation was found to be minimized by the lengthening of the substituent-ring distance and by distortion of the geometry.