Since the 1930s, new methods of drug delivery, such as implantable devices with drug release control, have been developed. However, manufacturing techniques require bulk due to high initial production costs. Three-dimensional (3D) printing, also known as additive manufacturing or rapid prototyping, allows the fabrication of personalized drug delivery that uses different materials and complex geometries with multiple release profiles, thereby eradicating high initial costs. Different studies have been developed showing the extensive potential of 3D printing for the pharmaceutical industry, and despite in-depth discussions that have been published, there is no comprehensive review of processes, materials, and effects in drug delivery applications thus far. This review aims to fill this gap by presenting the use of 3D printing technology for drug delivery, exposing the different variations of the technique according to the characteristics, material, and dosage form sought. There are seven main categories of 3D printing according to the standards jointly developed by International Organization for Standardization and American Society for Testing and Materials: material jetting, binder jetting, material extrusion, vat photopolymerization, powder bed fusion, sheet lamination, and directed energy deposition. There are different 3D fabrication processes used for drug delivery applications depending on the dosage form and material applied. In this context, polymers, glasses, and hydrogels represent the most frequent materials used. 3D printing allows different forms of drug dosage. Oral, topical, rectal and vaginal, parental and implantable are discussed in this paper, presenting the identification of the type of 3D printing technology, the active pharmaceutical ingredient, formulation, and pharmaceutical effect. The main aim of this paper is to offer insights to people from academy and industry who are interested in the advancement of drug delivery and in knowing the future directions in the development of 3D printing applications in this area.