The effect of surface oxyfluorination on low-density polyethylene (LDPE) film was studied in terms of surface functionality and surface energetics of the film surface, to which improvements in adhesion can be attributed. The formation of functional groups and surface free energy were confirmed by FTIR-ATR, XPS, and contact angle method. Adhesion strength of the oxyfluorinated LDPE film was investigated by the T-peel test. The total surface free energy increased with oxyfluorination time, with a progressive increase in the polar component together with a small decrease in the dispersive component of surface free energy. Consequently, oxyfluorinated LDPE film led to increased total surface free energy mainly due to the increase in the polar component, resulting in increased adhesion to copper foil. It was revealed that the oxyfluorinated LDPE film played an important role in improving the adhesion. A direct linear relationship is shown between surface free energy and the adhesion strength in this work.