Transition metal catalysis under visible-light irradiation has attracted considerable interest in recent years. With the objective of breaking free from the use of noble metals, and as an alternative to traditional photoredox and dual catalysis, the implementation of this strategy with 3d transition metal complexes capable of both absorbing visible light and enabling catalysis has very recently led to the development of efficient photocatalytic systems for challenging organic synthesis, including C–H bond functionalization reactions.