The formation of fibers by electrospinning has experienced explosive growth in the past decade, recently reaching 4,000 publications and 1,500 patents per year. This impressive growth of interest is due to the ability to form fibers with a variety of materials, which lend themselves to a large and rapidly expanding set of applications. In particular, coaxial electrospinning, which forms fibers with multiple core−sheath layers from different materials in a single step, enables the combination of properties in a single fiber that are not found in nature in a single material. This article is a detailed review of coaxial electrospinning: basic mechanisms, early history and current status, and an in‐depth discussion of various applications (biomedical, environmental, sensors, energy, catalysis, textiles). We aim to provide readers who are currently involved in certain aspects of coaxial electrospinning research an appreciation of other applications and of current results. Mix and match: In this Review, the basic operation of conventional electrospinning for the formation of homogenous fibers is briefly discussed and then coaxial electrospinning and process parameters for the formation of complex core‐sheath fibers are described. Early breakthroughs in coaxial electrospinning are introduced and then recent results are reviewed in some detail regarding the formation and properties of coaxial fibers for several key application areas: biomedical, sensors, textiles, energy, and catalysis.