The effect of boron nitride (BN) addition in carbon fiber reinforced resorcinol formaldehyde (C-RF) composites was explored in this study. Composites are altered with various weight proportions of boron nitride to make boron nitride incorporated carbon fiber reinforced resorcinol formaldehyde (BN-C-RF) composites. The ablation resistance of BN-C-RF composites was observed to be the maximum when the BN to RF ratio is 0.05:1. The thermomechanical properties of composites were studied. The thermally ablated composites were evaluated for their crystallographic changes. Formation of turbostratic carbon and turbostratic BN as well as changes in graphitization levels that occurred due to high-temperature exposure of composites were studied. The microstructural changes of the composites were analyzed by spectroscopy and microscopic studies. Results indicated the presence of oxides on the ablated surface, which was attributed to the reaction of BN with the available oxygen in the oxyacetylene flame environment and its resultant conversion to B2O3. The crystallographic transformations and microstructural changes, along with the oxidation of boron nitride, have enhanced the ablation resistance characteristics of the BN-C-RF system.