"I see it as my last because I don't know if I have the strength of mind to deal with football any more. So I'll do everything to turn up well, do everything to win with my country, to realise my greatest dream since I was little. And I hope I can do it," he added.
Neymar will be 34 in 2026 when the USA, Canada and Mexico will host the biggest competition in the world.
Aside from the Olympic gold, he won at the 2016 Olympic Games in Rio de Janeiro, Neymar's only trophy with the national team came in 2013 when Brazil lifted the Confederation Cup.