In this paper a novel integrated offline programming methodology for automated robot trajectory generation on free form surfaces is developed. Based on the computer-aided design model of a part, the tool model, task constraints and optimization criteria the trajectory is generated in an integrated manner. The proposed approach focuses on discretizing a surface into several ‘sections’ and simultaneous trajectory generation for the robot considering the local geometrical behavior of the surface and its effect globally. This research is primarily targeted toward generation of robot trajectory to spray paint a free form surface with desired paint thickness and minimum paint thickness deviation in a structured environment. The proposed approach was implemented on automobile parts to determine the effectiveness and robustness of designed algorithm. The simulation results and experimental validation on test surfaces revealed that the approach is flexible and efficient to handle variety in part geometry and the paint distribution.