The use of nickel–titanium (NiTi) alloys created a revolutionary impact in endodontic treatments. Shape memory and superelastic property of an NiTi alloy make the instrument more flexible, which improves the quality of the treatment by reducing the procedural errors. Even though these instruments show advanced metallurgical properties, it can lead to fracture due to fatigability. To improve the fracture resistance and enhance the clinical performance, various thermomechanical heat treatments had been introduced to these NiTi instruments. NiTi alloy undergoes phase transformation on heat treatment to upgrade the mechanical properties. This review article appraises the improved metallurgical properties of NiTi alloy by various thermomechanical heat treatment processes in addition with discussion of recently introduced thermomechanically altered NiTi endodontic instruments.