Chromatogeny grafting is an efficient method to hydrophobize lignocellulosic materials. Grafted papers are good candidates to replace plastic products in several applications requiring water barrier properties such as food packaging. However, chromatogeny grafting tends to reduce the sealability which is currently limiting the development of these materials. In this context, this study aims to investigate on the ultrasonic welding as a processing method to assemble papers coated with poly(vinyl alcohol) and grafted by chromatogeny. To reach such a goal, grafted and non-grafted papers, presenting different poly(vinyl alcohol) coating weight, have been welded under controlled conditions and peeled to evaluate the strength of welded joints. Results indicate that grafted-papers can be assembled by ultrasonic welding. However, it requires more severe processing conditions and the resulting peeling strength is lower than for non-grafted papers. Nevertheless, mechanical performances are quite satisfying in regard of the requirements of most packaging applications. Chromatogeny grafting modifies the adhesion mechanisms involved in the formation of the welded joints. Joint strength also increases with the poly(vinyl alcohol) coating weight which can be used as an adjusting parameter to optimize the adhesion. Overall, ultrasonic welding has proven its efficiency to assemble chromatogeny grafted-papers which is promising regarding the development of paper-based water barrier packaging solutions.