Background: Jellyfishes belong to the phylum Cnidarians with a wide range of size, from 22 centimeters to 2.5 meters. Jellyfishes have a worldwide distribution comprising over nine thousands species that approximately, 100 species are dangerous for humans. The venoms of these organisms contain biomolecules with extensive activities which could be used as a source of novel drugs in the future. Materials and Methods: The PubMed data bank was searched for the term “Jellyfish”. A total of 1677 papers were found. These papers were divided into three categories: medical, biomedical and biotechnological fields. The medical category was further divided into three subcategories comprising systemic manifestations, cutaneous manifestations and treatments for the stings of jellyfishes. The biomedical category was further subdivided into genomics, proteomics, and biology of venoms, mechanisms of actions and products of biomedical significance. In this part of systematic review, the biomedical and biotechnological and biotechnological fields were evaluated. Results: The genomics and proteomics of 24 species of jellyfishes had been studied in details. The mechanisms of actions of the venoms of 23 species were under investigations. The hematologic (hemolytic effects), cardiotoxic, neurotoxic, dermonecrotic, immunologic and cytotoxic presentations for the venoms were reported. Similar clinical presentations could be produced by different species of jellyfishes with a vast of molecular action mechanisms. Bioactive molecules with cytotoxic, anticancer, antibacterial and antioxidant effects were isolated from the venoms. Conclusion: The venoms of jellyfishes have bioactive molecules that produce a variety of complex intracellular interactions. Hence, the studies on the venomics of jellyfishes and the mechanisms of actions of their venoms could progress the therapeutic interventions and promise novel marine drugs.