Light-emitting materials, also referred to as luminescent materials, have been a topic of extensive research in diverse fields ranging from optoelectronics to bio-imaging. Therefore, much-needed efforts are directed toward the development and optimization of novel luminescent materials. In the case of targeted drug delivery and light-activated therapy, complexity arises with the inherent toxicity of certain kinds of drugs as well as the intricacy involved in the treatment of diseases. Therefore, this chapter is focused on the study of various types of luminescent materials, which not only improve the efficacy of this therapeutic treatment but can also reduce the side effects when interacting with living cells. This chapter also highlights the basic principle of luminescence and the types of luminescence suitable for applications in targeted drug delivery and therapeutic treatments. Also, relatively advanced luminescent materials, such as upconversion nanoparticles (UCNPs), carbon quantum dots (CQDs), metal–organic frameworks (MOFs), and polymeric-based nanoparticles (PNPs), have been discussed. Although these materials have shown better results in regard to real-time detection and tracking capabilities when compared with traditional fluorescent materials, they also face certain challenges. Hence, this chapter emphasizes both the advantages and disadvantages faced by the aforementioned materials in order to fully leverage their practical applications.