The effect of high-temperature annealing on tungsten (W) films deposited on silicon carbide (SiC) with and without a titanium nitride (TiN) diffusion barrier was examined as a function of time. Evolutions in phase composition, surface morphology, and roughness from annealing at 1273 K were investigated for up to 24 h. Without a TiN diffusion barrier, solid state reactions between the W film and SiC substrate led to the formation of W5Si3, W2C, and WC species and the rise of an inhomogeneous surface structure that was initially web-like and later discontinuous. Severe roughening on the order of the initial film thickness was observed. Incorporation of a 100 nm TiN diffusion barrier suppressed the formation of W5Si3 and W2C and only trace WC could be detected due to species diffusion through TiN grain boundaries. Changes in the surface structure and roughness were minimal. The results of this work warrant consideration of TiN as an effective diffusion barrier for W on SiC systems where structural stability at high temperatures is highly desired.