Messi, 35, had indicated prior to the tournament that it would be his last, with playing at the 2026 event to be held in North America appearing too far away.
Winning the World Cup has loomed as the former Barcelona star’s coronation as the greatest, with constant comparisons to Diego Maradona along with Cristiano Ronaldo.
Messi played a key part in Argentina’s semi-final success over Croatia with a goal and an assist for Julian Alvarez who bagged a double.
“I am proud to be able to finish my World Cup journey playing this final,” Messi told reporters.
“What I’m experiencing is exciting. Sunday will be my last game in a World Cup.
“It will be many years before the next one and I don’t think I’ll be able to make it, so I hope I can finish in the best way.”
Messi has enjoyed an excellent tournament, netting five goals, as he aims to go one better than in 2014 when Argentina were runners-up to Germany.
“I’m enjoying it all very much,” Messi said. “I feel good. I feel strong to face every game. We have been making a big sacrifice.
“The last game we played was with extra time. That was not easy at all. We were tired, but the group got strength. We played a very important game. We knew it was going to be the match it was.
“I’m very happy. Throughout this World Cup I’ve been having a lot of fun and, luckily, I was able to help the group to get things done.”