The former Stoke City midfielder was part of Sir Alf Ramsey's iconic 1966 squad.
He also played for Newcastle United and Arsenal during a career which spanned two decades.
Eastham will forever be remembered as the man who changed football's old 'retain and transfer' system.
In 1959, he went on strike for eight months to force Newcastle to let him join Arsenal after his contract expired.
At the time, clubs were allowed to keep players registered beyond their contract expiry date, in order to make them stay.
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However, Eastham emerged victorious over the Magpies and the Football Association during a three-week High Court trial in 1963 - which led to major reforms in the transfer market and the introduction of a tribunal.
Speaking about his impact last year, the football legend said: "You were a slave to the club.
"Going to court needed to be done. It needed to come out from the shadows.
"Players needed to be getting the money they were supposed to get. Everybody's getting the just rewards now."
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On the pitch, besides being a key member of the 1966 World Cup winning England squad, Eastham is best remembered for his time at Stoke.
He spent more than eight seasons at the club, making 194 league appearances, and managed them for a short spell between 1977/78.
The Championship side said in a statement: "The Stoke City Football Club family is immensely saddened by the passing of club legend George Eastham OBE at the age of 88.
"George was signed by the Potters for a £35,000 fee shortly after being part of England's 1966 World Cup winning squad.
"He went on to represent the club for eight seasons in the top division of the English game and was a two-time FA Cup semi-finalist in red and white.
"He is perhaps best remembered as the man whose goal secured the 1972 League Cup in a 2-1 victory over Chelsea at Wembley.
"The Potters will wear black armbands for the fixture against Sheffield Wednesday (on Saturday) as a mark of respect.
"Our thoughts are with George's family and friends at this difficult time."