We use WIEN2K to conduct density functional theory computations to explore the structural, thermodynamic, optoelectronic, and mechanical properties of fluoroperovskites QMnF3(Q = Ga, In). The application of the Birch–Murnaghan equation to the energyversusvolume, formation energy, and tolerance factor confirms the structural stability of these two QMnF3(Q = Ga, In) materials. The thermodynamic stability of the compounds is confirmed by the results of the phonon calculation, while the mechanical stability is confirmed from the values of the elastic constants. GaMnF3demonstrates a high capacity to withstand both compressive and shear stresses. A lower bulk modulus is responsible for the weaker ability of InMnF3to endure changes in volume. Compared to GaMnF3, InMnF3possesses rigidity having greater shear modulus, indicating greater resistance to changes in shape. However, both compounds are characterized as mechanically brittle, anisotropic, and ductile. The band structure that was determined indicates that both GaMnF3and InMnF3exhibit a metallic character. The density of states analysis further supports the metallic nature of GaMnF3and InMnF3. In GaMnF3, the “Mn” and “F” atoms in the valence band significantly participate in the total density of states, whereas in InMnF3, both “Mn” and “F” atoms also dominate the total density of states. The values ofε1(0) computed for GaMnF3and InMnF3are positivei.e.> 0, and agree with Penn's model. We calculate the optical properties for both GaMnF3and InMnF3and the potential of these materials of interest for applications in optoelectronic gadgets including light-emitting diodes is attributed to their absorption in the ultraviolet-visible zone. We believe that this work may provide comprehensive insight, encouraging further exploration of experimental studies.