The mainstream applications of visible-light photoredox catalysis predominately involve outer-sphere single-electron transfer (SET) or energy transfer (EnT) processes of precious metal Ru-II or Ir-III complexes or of organic dyes with low photostability. Earth-abundant metal-based (MLn)-L-n-type (M=metal, L-n=polydentate ligands) complexes are rapidly evolving as alternative photocatalysts as they offer not only economic and ecological advantages but also access to the complementary inner-sphere mechanistic modes, thereby transcending their inherent limitations of ultrashort excited-state lifetimes for use as effective photocatalysts. The generic process, termed visible-light-induced homolysis (VLIH), entails the formation of suitable light-absorbing ligated metal-substrate complexes ((MLn)-L-n-Z; Z=substrate) that can undergo homolytic cleavage to generate Mn-1Ln and Z(.) for further transformations.