Gene therapy signifies a transformative revolution in hemophilia care, providing the possibility for sustained endogenous synthesis of coagulation factors and limiting the need for external factor supplementation. Preliminary experiments in hemophilia B via adeno-associated viral (AAV) vectors encountered constraints owing to immunological reactions and temporary translation. Progress in vector technology, particularly via self-complementary AAV innovation and codon-optimized mini-factor IX (FIX) concepts, has markedly improved transduction performance and prolonged FIX activity. Initial investigations have shown encouraging outcomes, with certain individuals sustaining consistent FIX expressions for more than 8 years; hence, decreasing yearly bleeding incidents and requiring preventive therapy. The development of gene therapy for hemophilia A has encountered substantial obstacles owing to the enormous size of the factor VIII (FVIII) gene. The recent experiments using AAV serotypes 5 (AAV5) vectors that encode B-domain-deleted FVIII constructs have shown sustained levels along with substantial decreases in hemorrhage incidents. Research has shown prolonged FVIII expression, with some individuals attaining almost normal coagulation efficiency. Phase III studies have validated long-term effectiveness and safety, with transient transaminase elevations being the most common adverse event. Notwithstanding these advancements, difficulties persist, including immunological reactions to vector capsids, hepatotoxicity, and unpredictability in translation levels. Innovative approaches including lentiviral vectors, gene-editing technologies, and novel customized connection strategies demonstrate possibilities for enhancing the effectiveness of gene therapy. Continuous clinical research and improvement in delivery systems will be crucial in substantiating gene therapy as a definitive approach for hemophilia.