Two-dimensional (2D) transition metal carbides/nitrides (MXenes), since their discovery in 2011, have attracted great attention in the fields of energy storage, catalysis, sensors, electromagnetic interference shielding and microwave absorption and so on, owing to their special 2D layered structure, excellent electrical conductivity and electrochemical properties. In recent years, with the deep understanding of MXenes, the research on the realm related to optoelectronic properties has been widely concerned. Unlike other application fields, optoelectronic devices based on MXenes focus on extending semiconductor properties, including tunable band gap of the MXenes via design of the surface functional groups and layer control, etc., so as to achieve their transformation from metal to semiconductor properties. This paper revolves around the photoelectric properties of MXenes, mainly introduce its application in flexible optoelectronic devices, and systematically describe their current status and trend in transparent electronic devices, photodetectors, image sensors, transistors, and artificial neural vision network systems. The challenges and future development prospects of MXenes-based flexible optoelectronic devices are also proposed.