In this work, first-principles calculations were utilised to study the structural, magnetic and electronic properties of Mn$_2$PtZ (Z = V, Co) based on density functional theory (DFT). These compounds are predicted to be more stable in the Cu$_2$MnAl structure and the FM ground state is energetically favourable, withmagnetic moments of 4.93 and 9.04 $μ$$_B$/f.u. for Mn$_2$PtV and Mn$_2$PtCo compounds, respectively. Additionally, the computed total magnetic moments of both compounds agree well with the Slater–Pauling rule, MT = NV−24, andthe main contribution in these magnetic moments emanates from Mn atoms for both materials. Through the results on the spin-polarised electronic properties (band structures and densities of states), it is found that both alloys reveala complete half-metallic (HM) character with a half-metallic gap using GGA+U+TB-mBJ approximation.