This highlight focuses on various luminescent complexes with different transition metal centres of d⁶, d⁸ and d¹⁰ electronic configurations. Through the systematic study on the variation of ligands, structural and bonding modes of different metal centres, the structure-property relationships of the various classes of luminescent transition metal complexes can be obtained. With the knowledge and fundamental understanding of their photophysical behaviours, their electronic absorption and luminescence properties can be fine-tuned. Introduction of supramolecular assembly with hierarchical complexity involving non-covalent interactions could lead to research dimensions of unlimited possibilities and opportunities. The approach of “function by design” could be employed to explore and exploit the potential applications of such luminescent transition metal complexes for future development of luminescent materials.