Extracellular vesicles encompass several types of very diverse bioparticles composed by a lipid bilayer, without a functional nucleus, which contain information in the form of proteins, lipids, and nucleic acids, such as DNA, RNA, or microRNA. Extracellular vesicles are an important way of communication between cells. They can mediate intercellular communication, with a very wide range of functions in both physiological and pathological conditions. It is already recognized that extracellular vesicles can promote coagulation and bone regeneration, allow reticulocyte maturation, modulate immune response, and mediate neurodegeneration, cardiovascular diseases, and host permissiveness during infections. These vesicles seem to present a relevant role in cancer progression, through oncogenic signalling, tumour microenvironment modulation and immunomodulation, which might influence tumour growth, invasiveness, angiogenesis, and metastasis. A better understanding of their origin, cargo, and functions in cancer, may be useful to develop new strategies for inhibiting oncologic development and the disease progression. Further research is needed in this area since several of extracellular vesicles’ roles are not yet fully studied. Considering the recent advances in the field of research of extracellular vesicles in cancer, it seems evident that they will play an increasingly important role in cancer diagnosis and prognosis through non-invasive diagnostic methods, such as liquid biopsy. Extracellular vesicles could be soon considered relevant biomarkers for cancer diagnosis and prognosis, as well as to therapeutic monitoring. Extracellular vesicles are also promising research targets as drug delivery agents. It is even hypothesized that extracellular vesicles could work actively against cancer. Extracellular vesicles-based therapies have just started being developed and researched, there is still a long way to go. We will see in the future how far they can take us in the fight against cancer.