Cyanobacteria are ubiquitously distributed oxygenic photosynthetic prokaryotes, present even in extreme environments. Many cyanobacteria have been found to be excellent sources of proteins and bioactive compounds. Their cosmopolitan availability, abundant important bioactive compounds and their associated health benefits make cyanobacteria an ideal target for therapeutic applications. Cyanobacteria have a potential role in nutraceutics and are also important in drug development. Several studies have advocated the use of cyanobacteria and their active principles in the treatment of various diseases because cyanobacteria display anti-cancer, antibacterial, antiimmunosuppressive, anti-tumour, neuroprotective, and antiviral activities. Thus, in this review, we have summarized and updated the therapeutic applications of cyanobacteria in drug development, with the introduction of the new term "cyanotherapeutics".