Electrospinning has proven to be a simple, versatile, and useful technique for fabricating nanofibers from a rich variety of functional materials. In the past few years, we have witnessed tremendous research progress in understanding electrospinning mechanisms and their applications in controlled drug releasing and delivery. In this review, a brief description of the electrospinning process and fiber formation mechanisms is first provided. Then, a detailed review and discussion are given of the creation of secondary structures on electrospun fibers, such as porous and core-shell or hollow fiber structures. Finally, the drug-loading methods and drug release control mechanisms for drug-loaded electrospun fibers are summarized and discussed.