The Mozambican-born Eusebio died of a heart-attack at 0430 GMT, the club said. Eusebio, the 1965 European Footballer of the Year, is considered one of the best footballers of all time and best ever from Portugal.
He won ten league titles and five Portuguese cups in his 15 years at Benfica and was Portugal's top league scorer between 1964 and 1973.