Nanomaterials are being investigated for a vast variety of biomedical applications such as drug delivery, biosensors, tissue engineering, bioimaging etc. Most of the approaches utilize nano-scale biomaterials for developing unique functionalities required by fabricating biomedical devices. During the past few decades, photodynamic therapy (PDT) has been developed as an upcoming therapy for the treatment of various life threatening diseases such as cancer and some common bacterial infections. It is based on the photochemical reactions between light and tumour tissue generated using photosensitizing agents. The present chapter focuses on the various materials developed as photodynamic therapeutic agents and their future prospects.