As emerging biomaterials, framework nucleic acids (FNAs) have recently demonstrated great potential in the biomedical field due to their high programmability, biocompatibility, unique structural diversity, and precise molecular design capabilities. This review focuses on the applications of FNAs in cellular sensing and disease treatment. First, we systematically introduce the applications of FNAs in cellular sensing, including their precise recognition and response to the extracellular tumor microenvironment, cell membrane proteins, and intracellular biomarkers. Subsequently, we review the potential of FNAs in disease treatment, covering their applications and development in drug delivery, regulation of cell behavior, and immunomodulation. We also discuss the limitations and potential role of FNAs in personalized medicine, precision diagnostics, and advanced therapies. The broad application of FNAs is expected to drive significant breakthroughs in future biomedical technological innovations and clinical translation.