Metal complexes featuring acyclic diaminocarbene ligands have recently emerged as powerful emitters for prospective use in OLEDs and other electroluminescent technologies. Owing to their strong σ-donating properties and broad synthetic availability, acyclic diaminocarbenes have successfully challenged the application of other ancillary ligands for fine-tuning of luminescence emission. This review systematises the data reported concerning the preparation of luminescent metal complexes bearing acyclic diaminocarbene ligands, uncovers their photophysical properties as a function of the carbene ligand structure and metal characteristics, and draws attention to the potential of ADCs and the advantages that the application of metal-(acyclic diaminocarbenes) provides to the family of transition-metal-based phosphors.