The popularity of polyhedral oligomeric silsesquioxanes (POSS) for use in hybrid organic–inorganic materials and devices has grown in the past two decades due to desirable properties such as good thermal stability and biocompatibility, as well as their potential to be functionalized for a wide range of applications, from polymer composites to optoelectronics. Herein, the role of POSS for photonic applications, including sensing, bioimaging, and optoelectronic devices, is summarized. Functionalized POSS building blocks commonly incorporated with luminescent materials are identified, and areas of potential growth within the field are discussed. The addition of POSS to light‐emitting materials is widely shown to prevent aggregation in organic lumophores and inorganic nanocrystals, leading to reduced photoluminescence quenching. The POSS unit is also capable of acting as a passivating agent for nanocrystals and thin films, improving the emission quantum yields of photoluminescent materials and devices. POSS therefore offers the potential to enhance both the functional and photonic properties of cutting‐edge hybrid technologies.