Polymer matrix composites composed of poly(methyl methacrylate) (PMMA) and MXenes (Ti3C2T x ) are synthesized using direct solution blending and casting techniques. MXenes are a new family of two-dimensional materials. Both optical and conductivity properties of the resulting PMMA-MXene nanocomposite thin films are studied as a function of MXene concentration, for the first time. The resulting thin films are in the micrometer range (8.10–8.80 µm) in thickness. As the concentration of MXenes increases, the PMMA embeds MXenes, causing structural disturbance but without any change in the crystal structure. The MXene thickness in single-layered structure is 15–20 nm. Optical investigations such as UV-Vis absorption, absorption coefficient, extinction coefficient, and band gap have been reported to study the light absorption of nanocomposites. Resistivity measurement associated with electrical conductivity is studied. The relationship between optical responses and electrical conductivity is discussed. When compared to pure PMMA (1 × 10−14 to 1 × 10−13 S m−1), nanocomposites have electrical conductivity that is more than 3,000 times higher. The nanocomposites containing 15 wt% MXenes had the highest conductivity of 1.35 × 10−3 S m−1. Both the conductivity improvement and tunable optical findings accelerate the route of integrating MXenes into polymers to create more promising multifunctional composites for optoelectronic applications such as conductive electrodes, thin film transistors, and logic circuits.