The Brazil-born player, who was granted Portuguese citizenship after six years in the country, has been an ever-present in the Portugal side since a scoring debut in the 2-1 win over Brazil in 2002. However, this summer's FIFA World Cup in South Africa will be his last appearance on the international stage.
"I will end my cycle after the World Cup," Deco told Radio Globo. "For my age and because it is tiring, I will say goodbye to the national team after the World Cup."
Deco has won 71 caps for Portugal and was a key part of the team which finished runners up in UEFA EURO 2004. The 32-year-old also revealed he wants to return to Brazil at the end of the 2010/11 season, but only after winning the Premier League with Chelsea.
"The title for Chelsea will be my professional fulfilment," added Deco, who has won league titles with Porto and Barcelona.