Transition metal (TM)-borides are well known for their high thermal stability, high melting points, and excellent mechanical properties such as high hardness and Young’s modulus, making them suitable for a broad field of applications. However, TM-borides suffer from poor oxidation stability at high-temperature ranges. Therefore, improving the oxidation resistance is of great interest for coated high-performance components, where both – a combination of mechanical and oxidative resistance – are particularly desired. Within this study an architectural approach to protect TMB2 (TM = Hf, Ti, W) thin films from further oxidation is presented. For this purpose, different materials were investigated as protective layers on top of each boride system. The coatings have been deposited by PVD techniques. The phase formation, morphology, and mechanical properties (e.g., hardness and Young’s modulus) of all as deposited thin films were determined using X-ray diffraction (XRD), scanning electron microscopy (SEM), and nanoindentation. Thermogravimetric analyses up to 1400 °C in synthetic air was utilized to investigate the barrier function of these coatings with respect to the underlying TMB2 against oxidation. Subsequently, the long-term oxidation behavior of the synthesized films in ambient air at 1200 °C for 30 h was examined. In particular, the HfB2 and TiB2 systems were characterized by their oxidation resistance. High-resolution characterization techniques (i.e. TEM, HR-TEM, EDX) confirmed the good adhesion between the barrier top layers, as well as the unaffected diboride coatings and the sapphire substrates, respectively.