This study investigates the energy utilization and efficiency in thermally assisted machining (TAM) of a titanium alloy using numerical simulation. AdvantEdge finite element method (FEM) is used to conduct the simulation of orthogonal machining of the workpiece. Thermal boundary conditions are specified to approximate laser preheating of the workpiece material. The effects of operating conditions (preheat temperature, cutting speed, depth of cut, and rake angle) on mechanical cutting energy, preheat energy, and energy efficiency are investigated. The results show that preheating the workpiece reduces the cutting energy but increases the total energy in TAM. There is significant potential to maximize total energy efficiency in TAM by optimal design of heating strategies and machining conditions.