As renewable and sustainable clean energy, solar energy has the potential to address current energy shortage and reduce environmental pollution caused by fossil fuels consumption. In recent years, the third-generation thin-film solar cells, such as dye-sensitized solar cells (DSSCs) and perovskite solar cells (PSCs), have attracted widespread attention due to their low cost, abundant materials, and high photoelectric performance. However, these devices still face challenges in terms of charge transfer efficiency and operational stability for their commercialization. Two-dimensional (2D) MXene materials have emerged as promising candidates for improving the performance of thin-film solar cells due to their unique properties, including high specific surface area, rich surface functional groups, high conductivity, tunable work function, and hydrophilicity. This review summarizes the recent research progress of 2D MXene materials applied in new thin-film solar cells, focusing on the reaction mechanism that enhances the photoelectric performance of solar cells. Strategies such as using 2D MXene materials as additives for the perovskite layer and charge transport layer in PSCs, modifying the photoanode in DSSCs, and preparing varous electrodes, can effectively improve light absorption efficiency, carrier mobility, and charge extraction capability of the devices by adjusting band alignment, reducing work function, broadening the light absorption range, and creating a “pillar support effect”. As a result, the photoelectric performance and stability of the devices are enhanced. In conclusion, the perspectives highlights the current research progress and challenge faced by 2D MXene materials in novel thin-film solar cells.