Abstract Mesoporous silica stands out as a remarkable, low-density transparent material characterized by well-defined nanometric pore sizes. It is available in various morphologies, including monoliths, nanoparticles, and films. This material plays a pivotal role in numerous technological applications, both independently and as a component in hybrid composites, acting as a host for a diverse range of inorganic and organic materials. Among the synthetic routes, we accounted for the sol–gel method because of its large success in producing both nanoparticles and bulk mesoporous silica. This review focuses on exploring the optical properties of mesoporous silica and mesoporous silica-based composites, delving into how the huge void space within mesoporous silica can be harnessed across various fields: thermal and electrical insulations, photonics, environmental devices, or nanocargos for drugs and bioimaging. This comprehensive examination underscores the multifaceted potential of mesoporous silica, positioning it as a key player in the development of innovative solutions across various scientific domains.