The novel 2D materials, MXenes, have many remarkable properties, but their stability against oxidation is a major bottleneck in their applications. In this study, we have investigated the stability of Ti3C2Tx MXene for up to 365 days under different conditions, e.g., in liquid form in different solvents, in dried form when coated at polyethylene terephthalate (PET) substrate, and during the application of Ti3C2Tx MXene in polymer-dispersed liquid crystal- (PDLC-) based smart windows as conducting electrodes. In liquid form, the MXenes were dispersed in different solvents including an antioxidant in DI water and other organic solvents, and the corresponding color change was analyzed. To estimate the stability in dried form, the MXenes were coated on PET substrates and their relative sheet resistance change, i.e., , where is the initial resistance, was investigated under different conditions including MXene passivated with polymers and coated films stored under different environments. In the case of the MXene application-based stability study, the stability was investigated by using the MXenes as conducting electrodes in a switchable smart window application. The switchable behavior was observed by applying voltage (0-50 V) after different durations of up to 365 days. The MXene used in smart windows was preserved for a long time without additional treatment to MXene.