The advent of nanotechnology has provided unprecedented opportunities for nanomedicine. Electrospun nanofibers have some astounding features such as high loading capacity, extremely large surface area and porosity, high encapsulation efficiency, ease of modification, combination of diverse therapies, low cost and great benefits. These remarkable structure-dependent properties have far reaching application potential in cancer diagnosis and therapy such as ultra-sensitive sensing systems for point-of-care cancer detection, targeted cancer cell capture, and functional and smart anticancer drug delivery systems. This review summarizes the principal mechanism of electrospun nanofibers and a variety of modified electrospun nanofibers, illustrates their application in biosensors for cancer detection, and enumerates their application in implantable drug delivery for cancer therapy.