Gene therapy and genetic engineering are transforming the landscape of personalized and regenerative medicine by offering precise, targeted corrections at the genetic level. These technologies enable the replacement, repair, or regulation of defective genes using viral or non-viral delivery systems, significantly altering the course of inherited and acquired diseases. In tissue engineering, gene editing plays a pivotal role in programming stem cells, enhancing scaffold-cell interactions, and boosting tissue regeneration. Breakthroughs such as CRISPR-Cas9, base editing, and prime editing allow high-fidelity genomic modifications, minimizing off-target effects and increasing clinical feasibility. Gene therapy and genetic engineering are also being integrated into smart biomaterial systems and synthetic biology platforms to provide controlled release and spatially defined gene expression. As regulatory frameworks adapt, more gene-modified cell and tissue products are entering early-stage trials, suggesting a shift toward curative and adaptive solutions for complex diseases.