Gene therapy is a novel approach that involves changing the expression of a person’s genes to treat, cure, and/or ultimately prevent a disease. It may involve replacing a disease-causing gene with a healthy copy, adding a new gene to help treat a disease or deficiency, inactivating a gene that is not functioning properly, or permanently changing a gene on a patient’s genome. Since its inception, much progress has been made in advancing gene therapy delivery and gene editing technology, and the field has seen unprecedented development with a wave of therapeutic platforms that have gained regulatory approval worldwide ranging from cancer therapies to treating monogenic diseases. One of the most critical factors in gene therapy is deciding the appropriate gene delivery method into the target tissue/cells, and viruses have been the top choice vectors due to their natural tropism to transduce and infect cells. This chapter will focus on the most common viral vectors used in gene therapy, their biology, clinical applications, and production strategies, highlighting approved platforms, adverse events, and regulatory impacts. In addition, we will review the most recent gene editing tools and their application on gene therapy, discussing the analytics required to ensure that the viral vector platforms can be validated and approved for the clinic, their challenges, and future outlooks.