The identification of tumor-derived components in biofluids, such as blood, by minimally invasive or non-invasive methods, known as liquid biopsy, is a groundbreaking technique with great promise for cancer care. Liquid biopsies are capable of effectively identifying genomic and transcriptomic changes, offering a more thorough understanding of the diverse tumor profile compared to tissue biopsies alone. Liquid biopsies have the potential to aid in the diagnosis, prognosis, and selection of therapy. They may also be used with existing monitoring tools to track the progression of illness and the response to treatment in real-time. Specifically, these tests may detect even small amounts of remaining illness, forecast the likelihood of disease development, and determine the reasons for treatment resistance. This enables more timely adjustments to treatment plans. This review compiles the latest information on the function and promise of liquid biopsies in diagnosing and monitoring cancer patients. The data presented highlight the advantages of liquid biopsies, demonstrating their potential to enhance the detection and monitoring of many kinds of tumors in the near future. Nevertheless, while there is increasing evidence to support the usefulness of these tools in cancer therapy, many constraints must to be addressed before they can be effectively integrated into standard clinical practice.