In this chapter, the aggregation-induced emission (AIE) and solid-state luminescence of boron clusters, mainly o-carborane, are described. Since the discovery of AIE from the conjugated polymers containing o-carboranes in the main chain, much effort has been devoted to clarifying the mechanism on the suppression of aggregation-caused quenching (ACQ) and solid-state luminescence to develop applications based on AIE and crystallization-induced emission (CIE) properties of aryl-modified o-carboranes. From the mechanistic studies, it was shown that AIE is attributable to charge transfer (CT) emission at the initial stage. Afterward, the twisted intramolecular charge transfer (TICT) process was proved in the crystalline state. More recently, solid-state excimer emission has also been discovered. The various mechanisms on solid-state luminescence will be illustrated. We will mainly survey the progresses in developing functional materials having stimuli-responsive luminochromism regarding the solid-state excimer emission. Furthermore, it has been reported recently that nido-carborane not only exhibits diverse luminescence behaviors but also changes its luminescence properties depending on the type of added cation. We will also discuss these molecules in detail.