The 35-year-old arrived at Selhurst Park on a two-year deal in August 2019 after he had been released by Chelsea.
"After much thought and deliberation, I can confirm that I have left Crystal Palace," Cahill, who scored one goal in 45 league games, said on social media.
Cahill won the Premier League, FA Cup, League Cup, Champions League and Europa League during his time at Chelsea.
The former Bolton and Aston Villa player was capped 61 times by England before stepping back from international duty after the 2018 World Cup.
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