Solution-processed solar cells are appealing because of the low manufacturing cost, the good compatibility with flexible substrates, and the ease of large-scale fabrication. Whereas solution-processable active materials have been widely adopted for the fabrication of organic, dye-sensitized, and perovskite solar cells, vacuum-deposited transparent conducting oxides (TCOs) such as indium tin oxide, fluorine-doped tin oxide, and aluminum-doped tin oxide are still the most frequently used transparent electrodes (TEs) for solar cells. These TCOs not only significantly increase the manufacturing cost of the device, but also are too brittle for future flexible and wearable applications. Therefore, developing solution-processed TEs for solar cells is of great interest. This paper provides a detailed discussion on the recent development of solution-processed TEs, including the chemical synthesis of the electrode materials, the solution-based technologies for the electrode fabrication, the optical and electrical properties of the solution-processed TEs, and their applications on solar cells.