This research presents the structural, optical, elastic and electronic properties of cubic Barium based halide-Perovskites in combination with Al and Tl elements of the form XBaF3 (X= Al and Tl). The density functional theory (DFT) with the generalized gradient approximation of Perdew–Burke–Ernzerhof (GGA-PBE) and the Trans-Blaha modified Becke Johnson (TB-mBJ) approximation are employed for the consideration of exchange correlation effects. Structurally these compounds are found to be stable based on the structural optimization curves. The computed bands structure with TB-mBJ confers precise electronic properties of these materials as it is a precise and an accurate approximation for bands structure prediction. The computation of bands structure for both the materials reveals a semiconducting nature having a direct band gap from X-X (X-point in the reciprocal lattice space to X-symmetry points), having values lying from 0 eV at Fermi level to 3.75 eV for TlBaF3 and 4.36 eV for AlBaF3. The total and partial densities of states, as well as their contribution to the different bands are investigated and evaluated, i-e TDOS and PDOS are exploited. The IRelast package is used to calculate the elastic constants (ECs) of these crystals, with cubic symmetries, which can then be used to explore elastic and mechanical characteristics. Elastic properties shows that the compounds of interest are mechanically stable, anisotropic and ductile in character. Besides this, due to the high value of shear modulus "G," these materials demonstrate resistance to plastic deformation. It is noticed that these compounds are transparent for incident photons based on their optical properties. To our best understanding, this is the first comprehensive theoretical computation of these compounds which presents structural, optical, electronic and elastic properties that has yet to be confirmed experimentally.