2D materials display very promising intrinsic material properties, with mul-tiple applications in electronics, photonics, and sensing. In particular layered platinum diselenide has shown high potential due to its layer-dependent tunable bandgap, low-temperature growth, and high environmental stability. Here, the conformal and area selective (AS) low-temperature growth of layered PtSe₂ is presented defining a new paradigm for 2D material integra-tion. The thermally-assisted conversion of platinum which is deposited by AS atomic layer deposition to PtSe₂ is demonstrated on various substrates with a distinct 3D topography. Further the viability of the approach is presented by successful on-chip integration of hybrid semiconductor devices, namely by the manufacture of a highly sensitive ammonia sensors channel with 3D topography and fully integrated infrared-photodetectors on silicon photonics waveguides. The presented methodologies of conformal and AS growth therefore lay the foundation for new design routes for the synthesis of more complex hybrid structures with 2D materials.