In this paper, a method for online monitoring and correcting robot-guided fused deposition modeling is presented. For development a six-axis industrial robot was equipped with a 3D printing nozzle and used for 3D printing. Additionally, two laser line sensors were mounted next to the printing nozzle at the robot’s flange for capturing process data. By comparing CAD planning data to a point cloud of a workpiece printed with the robot, the measuring accuracy of the system is presented. For online monitoring and correcting, the measurement data of those sensors are analyzed for the unique structure of the edge of the currently printed layer. By detecting this edge, relevant process parameters are identified and compared with the planning data. Based on this comparison, corrections are derived and used for adjusting the robot’s trajectory. Furthermore, a concept for generating comparative measurement data in a simulation environment is presented.