Unsaturated carbon–carbon bonds are one of the most common and important structural motifs in many organic molecules, stimulating the continuous development of general, efficient and practical strategies for their functionalization. Here, we report a one-pot difunctionalization of alkynes via a photoredox/nickel dual-catalysed three-component cross-coupling reaction under mild conditions, providing access to a series of highly important tri-substituted alkenes. Notably, in contrast to traditional methods that are based on the steric hindrance of the substrates to control the reaction selectivity, both E- and Z-isomers of tri-substituted alkenes, which are often energetically close, can be obtained by choosing an appropriate photocatalyst with a suitable triplet state energy. Beyond the immediate practicality of this transformation, this newly developed methodology might inspire the development of diverse and important one-pot functionalizations of carbon–carbon multiple bonds via photoredox and transition-metal dual-catalysed multicomponent reactions.