Cancer remains one of the leading causes of death worldwide. Its complex pathogenesis and metastasis pose significant challenges for early diagnosis, underscoring the urgent need for innovative and non-invasive tumor screening methods. Exosomes, small extracellular vesicles that reflect the physiological and pathological states of their parent cells, are uniquely suited for cancer liquid biopsy due to their molecular cargo, including RNA, DNA, and proteins. However, traditional methods for exosome isolation and detection are often limited by inadequate sensitivity, specificity, and efficiency. Nanopore technology, characterized by high sensitivity and single-molecule resolution, offers powerful tools for exosome analysis. This review highlights its diverse applications in tumor screening, such as magnetic nanopores for high-throughput sorting, electrochemical sensing for real-time detection, nanomaterial-based assemblies for efficient capture, and plasmon resonance for ultrasensitive analysis. These advancements have enabled precise exosome detection and demonstrated promising potential in the early diagnosis of breast, pancreatic, and prostate cancers, while also supporting personalized treatment strategies. Additionally, this review summarizes commercialized products for exosome-based cancer diagnostics and examines the technical and translational challenges in clinical applications. Finally, it discusses the future prospects of nanopore technology in advancing liquid biopsy toward clinical implementation. The continued progress of nanopore technology not only accelerates exosome-based precision medicine but also represents a significant step forward in next-generation liquid biopsy and tumor screening.