Bioluminescent proteins such as luciferases are unique analytical tools with high sensitivity and wide dynamic ranges. However, applicability of the proteins has remained limited to reporter gene analysis. Split luciferase complementation technique is a new powerful strategy to detect protein-protein interactions and their related intracellular signaling in living cells. This review presents a summary of recent topics for the analysis of biological events using split luciferase complementation techniques. Different applications such as G-protein-coupled receptor (GPCR) screening, monitoring phosphorylations, protein-protein interactions, and pH differences in living tissues are described.