Plastics’ joining is used widely in food processing applications for the packaging of increasingly diverse food products. Laser transmission welding is an attractive proposition for such applications as it can significantly reduce tooling costs and potential downtime at product changeovers. In order to fulfil this promise in an industrial environment, an effective means of process parameter prediction is required. In this paper, goal driven optimization is conducted, utilizing numerical simulations as the basis for the prediction of optimal process parameters for the laser transmission welding of polyethylene film to a polypropylene substrate. A key consideration of the optimization process is the requirement for specific, pre-defined bonded track widths.