Cardiff, who were relegated to the second-tier Championship after one season, complained that their starting line-up had been leaked to Palace before their match in April, won 3-0 by the south London side.
Palace sporting director Iain Moody previously worked for Cardiff, but has denied any wrongdoing.
"The Premier League board has considered a complaint from Cardiff City regarding the conduct of a Crystal Palace official," the Premier League said in a statement.
"The board found that Crystal Palace breached Rule B.16 and has exercised its summary jurisdiction and fined the club."
The rule states that "in all matters and transactions relating to the League, each club shall behave towards each other club and the league with the utmost good faith".
(Reporting by Josh Reich, editing by Tim Collings)
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