The thermoelectric properties of hybrid graphene/boron nitride nanoribbons (BCNNRs) are investigated using the nonequilibrium Green's function approach. We find that the thermoelectric figure of merit () can be remarkably enhanced by periodically embedding hexagonal BN (-BN) into graphene nanoribbons (GNRs). Compared to pristine GNRs, the for armchair-edged BCNNRs with width index is enhanced 10–20 times, while the of nanoribbons with other widths is enhanced by just 1.5–3 times. As for zigzag-edge nanoribbons, the is enhanced 2–3 times. This improvement comes from the combined increase in the Seebeck coefficient and the reduction in the thermal conductance outweighing the decrease in the electrical conductance. In addition, the effect of the component ratio of -BN on the thermoelectric transport properties is discussed. These results qualify BCNNRs as a promising candidate for building outstanding thermoelectric devices.