Gene therapy has rapidly evolved as an innovative therapeutic strategy aimed at modifying genetic material to treat or prevent diseases at their molecular origin. Unlike conventional pharmacotherapy, which primarily alleviates symptoms, gene therapy focuses on correcting or regulating defective genes responsible for disease progression. This review provides a critical overview of gene therapy, including delivery systems, genome-editing technologies such as CRISPR-Cas9, and various therapeutic approaches. Recent clinical successes, particularly in chimeric antigen receptor T-cell (CAR-T) therapy and monogenic disorders, highlight its translational significance. However, challenges such as immune responses, off-target effects, ethical concerns, and high treatment costs remain barriers to widespread adoption. Regulatory frameworks and ongoing clinical trials are continuously addressing these issues. The integration of gene therapy with personalized medicine further enhances its potential in targeted treatment. Overall, gene therapy represents a paradigm shift toward precision medicine and holds promise as a future cornerstone of healthcare systems.