The present Invention discloses two robot assisted automated methods for application of decals on complex 3 dimensional surfaces without wrinkle and bubble. The method includes loading of objects having 3D surfaces on an object holding fixture manually from a conveyor belt, picking up a first application fixture automatically by a robot, peeling off the liner disposed on the decal manually and placing the decal on the first application fixture which holds the decal by suction, positioning the decal with exposed adhesive accurately on a first 3D surface of the object and switching off the suction automatically leaving the decal placed on the 3D surface of the object, placing the first application fixture back and picking up a second application fixture automatically by the robot for squeegee application, applying the second application fixture to complete the squeegee application by pressurizing the decal. The first application fixture is configured to be programmed to hold decals of different shape and size and the second application fixture is configured to be programmed to identify the 3D direction of squeezing pad motion within each region of such decals to eliminate the bubbles without wrinkling. The second method uses a mechatronic pick and place mechanism for picking up a decal from the decal stack and placing of the decal on the 3D surface of the object automatically.