New technological tools are increasingly being applied in orthognathic surgery. Advanced techniques of imaging, diagnosis and treatment planning development, as well as simulation, guidance and evaluation of the treatment outcome are gradually taking the place of conventional techniques, enabling three-dimensional (3D) digital planning and personalized treatment of craniofacial deformities. Conventional and advanced three-dimensional techniques, such as three-dimensional ultrasound imaging (3D U/S), three-dimensional magnetic resonance imaging (3T-MRI), three-dimensional computed tomography (CT) and cone beam computed tomography (CBCT) imaging, as well as combinations of these techniques, are classified as modern technological tools, while robotic surgery and four-dimensional video stereophotogrammetry have already begun to find clinical application. In conclusion, advances in diagnostic and planning techniques in orthognathic surgery present many preoperative, intraoperative and postoperative advantages, significantly reducing the chances of complications and providing safety, accuracy and a high level of medical care. The aim of this literature review is to collect, present and evaluate new data and contemporary diagnostic methods in the field of orthognathic surgery.