<p>MXenes, a recently discovered class of two-dimensional (2D) materials consisting of transition metal carbides, nitrides, or carbonitrides. In MXenes, the presence of defects at atomic level and functional groups are recognized for their significant impact on the physical behavior and functional properties. So, in this work density functional theory (DFT) approach is employed to investigate a non-terminated Sc₂C MXenes monolayer is considered with functionalization (F, O and OH functional groups) compositions; Sc₂CO_x(OH)_xF_1−2x, Sc₂CF_x(OH)_xO_1−2xand Sc₂CF_xO_x(OH)_1−2x and the introduction of carbon vacancy (Vc) in it as: Sc₂C-Vc, Sc₂CO_x(OH)_xF_1−2x-Vc, Sc₂CF_x(OH)_xO_1−2x-Vc and Sc₂CF_xO_x(OH)_1−2x-Vc. Negative binding energy of all considered compositions indicates their stability. Among all the designed compositions, the Sc₂C-Vc, Sc₂CF_0.125(OH)_0.125O_0.75, Sc₂CF_0.25O_0.25(OH)_0.5, and Sc₂CF_0.25O_0.25(OH)_0.5-Vccompositions exhibited a very narrows band gap indicating its semiconducting behavior as compared to non-terminated Sc₂C and all other mixed functionalized Vc composition. Further we investigated the effect of mixed functionalization and Vc introduction on optical properties such as absorption coefficient, dielectric function, conductivity, refractive index, reflectivity and loss function. Among all composition in case of mixed functionalization in lower energy region non-terminated Sc₂C and in higher energy region mixed functionalized compositions while in case of Vc compositions in lower energy region Sc₂C-Vc and in higher energy region other Vc compositions showed maximum value of absorption, refractive index and conductivity value.</p>