Witsel ends his international career with 140 caps, 12 goals, and eight assists. His last appearance was in the quarter-finals of the 2026 World Cup, when Belgium were eliminated by Spain, and he played for about 30 minutes.
The footballer announced his retirement on social media, with a message in which he thanked everyone who supported him throughout his international career:
"This time, it's the right one. I've made the decision to put an end to my international career," he announced.
"It's time to make way for the young players and the new generation. It was an immense pride to have given everything during these 18 years. I never would have imagined achieving so much when I started, at just 18 years old.
"Thank you to the supporters. Thank you to all my teammates, all my coaches, and all the people within the federation who contributed, near or far, to my growth over all these years.
"Good luck to the team for the future. I'm certain its future will be bright. I love you, Belgium," Witsel said.
Van Bommel planned to call Witsel up
The retirement comes ahead of Belgium's first official matches in the Nations League under the guidance of new coach Mark van Bommel. The Dutch manager had wanted to include Witsel in the squad.
At club level, the midfielder plays for Nice in Ligue 1, after previously playing for teams such as Benfica, Zenit, Borussia Dortmund, Atletico Madrid, and Girona.