The Real Madrid attacker inspired his country to a playoff win over Sweden during qualifying and he has now targeted success in Brazil at the end of the season.
"Winning the World Cup would finish my career," he told Marca.
"First we have to think of the group stage but after that we'll see. Hopefully I can be champion of Europe and the world with Portugal."
Ronaldo, who will skipper his country at the World Cup, has scored 10 times in his last nine games for Portugal, while he has scored 47 times in total.