We present a computational research on investigating the structural, electronic, optical, magnetic, and thermoelectric properties of Pt doped and Pt-Cu/Au co-doped GaN using the Wien2k code. The PBE-GGA approximation is employed in Wien2k code using density functional theory. Study of electronic properties reveals that the d-states of Pt, Cu, and Au atoms participate actively in transferring electron from valence to conduction band and their addition as mono and co-doped formation turns the non-magnetic character of GaN to magnetic. A blueshift in absorption spectrum appear and absorption is more pronounced for Pt-Cu/Au co-doped GaN, suggesting the use of these materials for high energy UV optoelectronics, spintronics, photonic, and sensing devices. However, lower reflection and enhanced conductivity of Pt-Cu/Au co-doped materials in the UV region extends their potential applications in high frequency electronics. Moreover, higher ZT value of Pt@GaN suggest it a better thermoelectric source other than Pt-Cu/Au@GaN.