Developing new and efficient biosensor platforms for analyzing various biological agents and pesticides is a challenge in analytical chemistry for future research. MXenes, or 2D transition metal carbides, nitrides, and carbonitrides, are considered versatile sensing platforms owing to their adjustable configuration and rich surface chemistry. This study focused on the role of MXenes in photoelectrochemical applications, whose popularity has increased dramatically in the last decade due to their unique properties and functional structure. The effect of MXenes on photoelectrochemical sensing processes is discussed in depth. In addition, the review covers the latest trends in MXene-based photoelectrochemical sensors/biosensors, current research, and new strategies to follow. Moreover, the synthesis of MXenes with a green approach and integration of these procedures into photoelectrochemical sensing/biosensing applications have been studied in detail for the first time.