Wembanyama represented France at the 2019 FIBA U16 European Championship in Udine, Italy. In an 80–78 quarterfinal win over Croatia, he recorded 12 points, 21 rebounds and eight blocks. Wembanyama averaged nine points, 9.6 rebounds and a tournament-leading 5.3 blocks per game, leading France to a silver medal and earning all-tournament team honors. He competed at the 2021 FIBA Under-19 Basketball World Cup in Latvia. Wembanyama averaged 14 points, 7.4 rebounds and 5.7 blocks per game, and was named to the all-tournament team after leading France to the silver medal. He recorded 22 points, eight rebounds and eight blocks in an 83–81 loss to the United States in the final. Wembanyama set the FIBA record for blocks per game in a single tournament.