This paper explores the impact of europium (Eu) and yttrium (Y) doping on the electronic, magnetic, optical, elastic, and structural properties of SmMnO3 perovskites using the Quantum ESPRESSO code. The cohesive energy and tolerance factor calculations revealed that the perovskite can maintain structural stability up to 25% doping of Eu and Y. Bandgap calculations suggest that when Eu and Y are doped, the energy bandgap of pure SmMnO3 decreases significantly from 2.72 to 0.47 and from 2.72 to 0.76 eV, respectively. Doped SmMnO3 exhibits a UV shift and increased intensity in the absorption coefficient, while the reflectivity peak decreases. These changes in optical properties and bandgap due to Eu and Y doping make SmMnO3 a promising material for advanced applications in photovoltaics, UV photodetectors, and optoelectronic devices. The ferromagnetic property and total magnetic moment of SmMnO3 are found to be increased by Eu doping. Meanwhile, the magnetic moment gets reduced by Y doping. Curie temperature calculations indicate that Eu doping increases the Curie temperature from 255.35 to 314.28 K, while Y doping reduces it from 255.35 to 187.69 K. These changes in magnetic moment and Curie temperature suggest that the doped material is suitable to be used in magnetic sensors and storage devices. The calculated elastic constants, Young’s modulus, shear modulus, Poisson’s ratio, and B/G ratio suggest that both pristine and doped compounds under study show a ductile behavior.