Traditional semiconductor materials such as metal-oxide-based photoelectrodes have been extensively explored for energy and environmental applications. However, their performance is hindered by poor light absorption, high charge recombination rates, and low surface kinetics. The incorporation of metal–organic framework (MOF) and plasmonic structures into semiconductors is one of the most promising strategies to achieve performances beyond those of bare MOF and/or conventional semiconductors. This review summarises the rational design of semiconductor-based photoelectrodes incorporating MOFs and plasmonic metals for hybrid photoelectrochemical catalysis and photocatalysis, with a wide variety of parameters including photoactivity, conductivity, catalytic property, surface morphology, porous architecture and bandgap alignment. Moreover, applications of this new generation of composite photoelectrodes in water splitting, CO2 reduction and pollution degradation are discussed in detail. The challenges and prospects of plasmonic MOF nanocomposites in eco-friendly and cost-efficient technologies for practical applications in water splitting, CO2 reduction and environmental remediation are also highlighted.