The Malaysian, who has been chairman since 2010, is leaving to pursue other business opportunities.
He introduced business partner Vincent Tan - the Malaysian billionaire who now owns City - to the club when the Bluebirds were struggling financially under Peter Ridsdale.
A statement on Cardiff's official website said: "We wish to confirm that Dato Chan Tien Ghee (TG) has resigned as chairman and director of Cardiff City Football Club with immediate effect.
"TG is embarking on new career and business pursuits that requires his full attention. Given constraints of time and distance, TG believes he is unable to meet the demands of his position as chairman and board member of Cardiff City Football Club.
"We are greatly indebted to TG, who since joining in 2010 has been instrumental in the progress of the club to where it is today, and we wish to record our deep appreciation for his invaluable contributions and efforts."