Helicases are increasingly recognized as powerful ATP-driven nanomachines whose precise control over nucleic-acid dynamics positions them at the forefront of modern molecular medicine. By coupling ATP hydrolysis to mechanical motion, these enzymes unwind DNA or RNA, remodel complex secondary structures, and coordinate multi-protein repair or replication assemblies with remarkable accuracy. Their mechanistic versatility makes them attractive therapeutic targets: small-molecule inhibitors of viral helicases are advancing antiviral strategies, while modulation of human helicases involved in DNA repair is emerging as a promising approach in personalized cancer therapy. High-resolution structural studies and single-molecule imaging are now revealing how individual helicases step, pause, and coordinate ATP turnover, paving the way for rational drug design, synthetic biological systems, and innovative diagnostic platforms that leverage their dynamic capabilities. As our understanding deepens, helicases are evolving from fundamental biological motors to central tools shaping next-generation medical technologies.