In this work, we present a density functional theory (DFT) study of the structural, magnetic, electronic, mechanical, and optical properties of f-electron based ACmO3 and A′PuO3 perovskites in the cubic phase. Ground-state stability analysis shows that these compounds preferentially stabilize in the ferromagnetic configuration, providing a robust framework for exploring their magnetic properties. All investigated compounds exhibit cubic structures, as confirmed by the Goldschmidt tolerance factor. Density of states and band structure calculations reveal 100% spin polarization at the Fermi level, with spin-down band gaps in the range of 1.2–4.6 eV and total magnetic moments between 3 and 6 µB, confirming their half-metallic nature and potential for spintronic and memory device applications. The calculated Curie temperatures span 367–812 K, significantly above room temperature, with higher magnetic moments correlating with stronger ferromagnetic ordering. Negative formation energies confirm thermodynamic stability, while cohesive energies 11.8–20.7 eV reflect superior bonding strength. Elastic constant analysis based on Born criteria demonstrates mechanical stability across all compounds, with 16 out of 20 exhibiting ductile behavior and Young’s modulus ranging from 64.6 to 128.9 GPa. The calculated melting temperatures lie between 1366 and 2062 K, further confirming high-temperature endurance. Collectively, these features robust ferromagnetism, metallic conductivity, ductility and mechanical resilience highlight investigated perovskites as particularly promising candidates for advanced spintronic applications.